CWE-770
AllowedAllocation of Resources Without Limits or Throttling
Abstraction: Base · Status: Incomplete
The product allocates a reusable resource or group of resources on behalf of an actor without imposing any intended restrictions on the size or number of resources that can be allocated.
3022 vulnerabilities reference this CWE, most recent first.
GHSA-WRF2-2RCH-CMR9
Vulnerability from github – Published: 2022-05-17 04:31 – Updated: 2024-10-14 21:41python_scripts.py in Plone before 4.2.3 and 4.3 before beta 1 allows remote attackers to cause a denial of service (memory consumption) via a large value, related to formatColumns.
{
"affected": [
{
"package": {
"ecosystem": "PyPI",
"name": "Plone"
},
"ranges": [
{
"events": [
{
"introduced": "4.0"
},
{
"fixed": "4.2.3"
}
],
"type": "ECOSYSTEM"
}
]
},
{
"package": {
"ecosystem": "PyPI",
"name": "Plone"
},
"ranges": [
{
"events": [
{
"introduced": "4.3a1"
},
{
"fixed": "4.3b1"
}
],
"type": "ECOSYSTEM"
}
]
}
],
"aliases": [
"CVE-2012-5499"
],
"database_specific": {
"cwe_ids": [
"CWE-770"
],
"github_reviewed": true,
"github_reviewed_at": "2023-02-08T17:55:14Z",
"nvd_published_at": "2014-09-30T14:55:00Z",
"severity": "HIGH"
},
"details": "python_scripts.py in Plone before 4.2.3 and 4.3 before beta 1 allows remote attackers to cause a denial of service (memory consumption) via a large value, related to `formatColumns`.",
"id": "GHSA-wrf2-2rch-cmr9",
"modified": "2024-10-14T21:41:07Z",
"published": "2022-05-17T04:31:18Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2012-5499"
},
{
"type": "WEB",
"url": "https://access.redhat.com/errata/RHSA-2014:1194"
},
{
"type": "WEB",
"url": "https://access.redhat.com/security/cve/CVE-2012-5499"
},
{
"type": "WEB",
"url": "https://bugzilla.redhat.com/show_bug.cgi?id=874657"
},
{
"type": "PACKAGE",
"url": "https://github.com/plone/Plone"
},
{
"type": "WEB",
"url": "https://github.com/plone/Products.CMFPlone/blob/4.2.3/docs/CHANGES.txt"
},
{
"type": "WEB",
"url": "https://github.com/pypa/advisory-database/tree/main/vulns/plone/PYSEC-2014-41.yaml"
},
{
"type": "WEB",
"url": "https://plone.org/products/plone-hotfix/releases/20121106"
},
{
"type": "WEB",
"url": "https://plone.org/products/plone/security/advisories/20121106/15"
},
{
"type": "WEB",
"url": "http://rhn.redhat.com/errata/RHSA-2014-1194.html"
},
{
"type": "WEB",
"url": "http://www.openwall.com/lists/oss-security/2012/11/10/1"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
"type": "CVSS_V3"
},
{
"score": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N",
"type": "CVSS_V4"
}
],
"summary": "Plone is vulnerable to denial of service"
}
GHSA-WRM6-J53R-328Q
Vulnerability from github – Published: 2026-07-14 18:32 – Updated: 2026-07-14 18:32Allocation of resources without limits or throttling in HTTP/2 allows an unauthorized attacker to deny service over a network.
{
"affected": [],
"aliases": [
"CVE-2026-49788"
],
"database_specific": {
"cwe_ids": [
"CWE-770"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2026-07-14T17:16:54Z",
"severity": "HIGH"
},
"details": "Allocation of resources without limits or throttling in HTTP/2 allows an unauthorized attacker to deny service over a network.",
"id": "GHSA-wrm6-j53r-328q",
"modified": "2026-07-14T18:32:01Z",
"published": "2026-07-14T18:32:01Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-49788"
},
{
"type": "WEB",
"url": "https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-49788"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
"type": "CVSS_V3"
}
]
}
GHSA-WRWP-F8PQ-Q3QJ
Vulnerability from github – Published: 2024-03-26 18:32 – Updated: 2025-03-17 15:31In the Linux kernel, the following vulnerability has been resolved:
thermal: intel: hfi: Add syscore callbacks for system-wide PM
The kernel allocates a memory buffer and provides its location to the hardware, which uses it to update the HFI table. This allocation occurs during boot and remains constant throughout runtime.
When resuming from hibernation, the restore kernel allocates a second memory buffer and reprograms the HFI hardware with the new location as part of a normal boot. The location of the second memory buffer may differ from the one allocated by the image kernel.
When the restore kernel transfers control to the image kernel, its HFI buffer becomes invalid, potentially leading to memory corruption if the hardware writes to it (the hardware continues to use the buffer from the restore kernel).
It is also possible that the hardware "forgets" the address of the memory buffer when resuming from "deep" suspend. Memory corruption may also occur in such a scenario.
To prevent the described memory corruption, disable HFI when preparing to suspend or hibernate. Enable it when resuming.
Add syscore callbacks to handle the package of the boot CPU (packages of non-boot CPUs are handled via CPU offline). Syscore ops always run on the boot CPU. Additionally, HFI only needs to be disabled during "deep" suspend and hibernation. Syscore ops only run in these cases.
[ rjw: Comment adjustment, subject and changelog edits ]
{
"affected": [],
"aliases": [
"CVE-2024-26646"
],
"database_specific": {
"cwe_ids": [
"CWE-770"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2024-03-26T18:15:09Z",
"severity": "MODERATE"
},
"details": "In the Linux kernel, the following vulnerability has been resolved:\n\nthermal: intel: hfi: Add syscore callbacks for system-wide PM\n\nThe kernel allocates a memory buffer and provides its location to the\nhardware, which uses it to update the HFI table. This allocation occurs\nduring boot and remains constant throughout runtime.\n\nWhen resuming from hibernation, the restore kernel allocates a second\nmemory buffer and reprograms the HFI hardware with the new location as\npart of a normal boot. The location of the second memory buffer may\ndiffer from the one allocated by the image kernel.\n\nWhen the restore kernel transfers control to the image kernel, its HFI\nbuffer becomes invalid, potentially leading to memory corruption if the\nhardware writes to it (the hardware continues to use the buffer from the\nrestore kernel).\n\nIt is also possible that the hardware \"forgets\" the address of the memory\nbuffer when resuming from \"deep\" suspend. Memory corruption may also occur\nin such a scenario.\n\nTo prevent the described memory corruption, disable HFI when preparing to\nsuspend or hibernate. Enable it when resuming.\n\nAdd syscore callbacks to handle the package of the boot CPU (packages of\nnon-boot CPUs are handled via CPU offline). Syscore ops always run on the\nboot CPU. Additionally, HFI only needs to be disabled during \"deep\" suspend\nand hibernation. Syscore ops only run in these cases.\n\n[ rjw: Comment adjustment, subject and changelog edits ]",
"id": "GHSA-wrwp-f8pq-q3qj",
"modified": "2025-03-17T15:31:36Z",
"published": "2024-03-26T18:32:07Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2024-26646"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/019ccc66d56a696a4dfee3bfa2f04d0a7c3d89ee"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/28f010dc50df0f7987c04112114fcfa7e0803566"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/97566d09fd02d2ab329774bb89a2cdf2267e86d9"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/c9d6d63b6c03afaa6f185df249af693a7939577c"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H",
"type": "CVSS_V3"
}
]
}
GHSA-WV25-WJH7-WHJH
Vulnerability from github – Published: 2026-02-10 21:31 – Updated: 2026-02-10 21:31Connections received from the proxy port may not count towards total accepted connections, resulting in server crashes if the total number of connections exceeds available resources. This only applies to connections accepted from the proxy port, pending the proxy protocol header.
{
"affected": [],
"aliases": [
"CVE-2026-1848"
],
"database_specific": {
"cwe_ids": [
"CWE-770"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2026-02-10T19:15:51Z",
"severity": "HIGH"
},
"details": "Connections received from the proxy port may not count towards total accepted connections, resulting in server crashes if the total number of connections exceeds available resources. This only applies to connections accepted from the proxy port, pending the proxy protocol header.",
"id": "GHSA-wv25-wjh7-whjh",
"modified": "2026-02-10T21:31:29Z",
"published": "2026-02-10T21:31:29Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-1848"
},
{
"type": "WEB",
"url": "https://jira.mongodb.org/browse/SERVER-114695"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
"type": "CVSS_V3"
},
{
"score": "CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X",
"type": "CVSS_V4"
}
]
}
GHSA-WVGJ-PJC7-8FC4
Vulnerability from github – Published: 2022-05-24 19:19 – Updated: 2022-05-24 19:19A regular expression denial of service issue in GitLab versions 8.13 to 14.2.5, 14.3.0 to 14.3.3 and 14.4.0 could cause excessive usage of resources when a specially crafted username was used when provisioning a new user
{
"affected": [],
"aliases": [
"CVE-2021-39914"
],
"database_specific": {
"cwe_ids": [
"CWE-400",
"CWE-770"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2021-11-04T23:15:00Z",
"severity": "MODERATE"
},
"details": "A regular expression denial of service issue in GitLab versions 8.13 to 14.2.5, 14.3.0 to 14.3.3 and 14.4.0 could cause excessive usage of resources when a specially crafted username was used when provisioning a new user",
"id": "GHSA-wvgj-pjc7-8fc4",
"modified": "2022-05-24T19:19:55Z",
"published": "2022-05-24T19:19:55Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2021-39914"
},
{
"type": "WEB",
"url": "https://gitlab.com/gitlab-org/cves/-/blob/master/2021/CVE-2021-39914.json"
},
{
"type": "WEB",
"url": "https://gitlab.com/gitlab-org/gitlab/-/issues/289948"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L",
"type": "CVSS_V3"
}
]
}
GHSA-WVVP-C8QH-3CC5
Vulnerability from github – Published: 2026-07-14 18:31 – Updated: 2026-07-14 18:31In Roundcube Webmail before 1.6.17 and 1.7.x before 1.7.2, the TNEF decoder was subject to denial of service via a crafted compressed-RTF size.
{
"affected": [],
"aliases": [
"CVE-2026-62641"
],
"database_specific": {
"cwe_ids": [
"CWE-770"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2026-07-14T16:17:04Z",
"severity": "MODERATE"
},
"details": "In Roundcube Webmail before 1.6.17 and 1.7.x before 1.7.2, the TNEF decoder was subject to denial of service via a crafted compressed-RTF size.",
"id": "GHSA-wvvp-c8qh-3cc5",
"modified": "2026-07-14T18:31:56Z",
"published": "2026-07-14T18:31:56Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-62641"
},
{
"type": "WEB",
"url": "https://github.com/roundcube/roundcubemail/commit/6d1004fd3764a9606c53130b322c0f295c38be64"
},
{
"type": "WEB",
"url": "https://github.com/roundcube/roundcubemail/commit/bf253c72d4293c93fda511b8464fe9cb34b522c1"
},
{
"type": "WEB",
"url": "https://github.com/roundcube/roundcubemail/releases/tag/1.6.17"
},
{
"type": "WEB",
"url": "https://github.com/roundcube/roundcubemail/releases/tag/1.7.2"
},
{
"type": "WEB",
"url": "https://roundcube.net/news/2026/07/05/security-updates-1.6.17-and-1.7.2"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:L",
"type": "CVSS_V3"
}
]
}
GHSA-WW69-PX64-3PGV
Vulnerability from github – Published: 2026-01-31 00:30 – Updated: 2026-02-05 21:32IBM Db2 for Linux, UNIX and Windows (includes DB2 Connect Server) 11.5.0 - 11.5.9 and 12.1.0 - 12.1.3 could allow a local user to cause a denial of service when copying large table containing XML data due to improper allocation of system resources.
{
"affected": [],
"aliases": [
"CVE-2025-36123"
],
"database_specific": {
"cwe_ids": [
"CWE-770"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2026-01-30T22:15:53Z",
"severity": "MODERATE"
},
"details": "IBM Db2 for Linux, UNIX and Windows (includes DB2 Connect Server) 11.5.0 - 11.5.9 and 12.1.0 - 12.1.3\u00a0could allow a local user to cause a denial of service when copying large table containing XML data due to improper allocation of system resources.",
"id": "GHSA-ww69-px64-3pgv",
"modified": "2026-02-05T21:32:38Z",
"published": "2026-01-31T00:30:28Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2025-36123"
},
{
"type": "WEB",
"url": "https://www.ibm.com/support/pages/node/7257627"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
"type": "CVSS_V3"
}
]
}
GHSA-WWRG-2W5J-GRVX
Vulnerability from github – Published: 2023-08-03 18:30 – Updated: 2023-08-03 22:20Allocation of Resources Without Limits or Throttling in GitHub repository ikus060/rdiffweb prior to 2.8.0.
{
"affected": [
{
"package": {
"ecosystem": "PyPI",
"name": "rdiffweb"
},
"ranges": [
{
"events": [
{
"introduced": "0"
},
{
"fixed": "2.8.1"
}
],
"type": "ECOSYSTEM"
}
]
}
],
"aliases": [
"CVE-2023-4138"
],
"database_specific": {
"cwe_ids": [
"CWE-770"
],
"github_reviewed": true,
"github_reviewed_at": "2023-08-03T22:20:11Z",
"nvd_published_at": "2023-08-03T15:15:36Z",
"severity": "MODERATE"
},
"details": "Allocation of Resources Without Limits or Throttling in GitHub repository ikus060/rdiffweb prior to 2.8.0.",
"id": "GHSA-wwrg-2w5j-grvx",
"modified": "2023-08-03T22:20:11Z",
"published": "2023-08-03T18:30:35Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2023-4138"
},
{
"type": "WEB",
"url": "https://github.com/ikus060/rdiffweb/commit/feef0d7b11d86aed29bf98c21526088117964d85"
},
{
"type": "PACKAGE",
"url": "https://github.com/ikus060/rdiffweb"
},
{
"type": "WEB",
"url": "https://huntr.dev/bounties/1b1fa915-d588-4bb1-9e82-6a6be79befed"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.0/AV:L/AC:L/PR:H/UI:N/S:U/C:L/I:L/A:L",
"type": "CVSS_V3"
}
],
"summary": "RDiffWeb vulnerable to Allocation of Resources Without Limits or Throttling"
}
GHSA-WWX5-JQ7H-RP7V
Vulnerability from github – Published: 2026-06-09 18:31 – Updated: 2026-06-09 18:31Hermes WebUI before version 0.51.270 contains a resource exhaustion vulnerability that allows unauthenticated remote attackers to degrade service availability by repeatedly calling the passkey options endpoint without completing assertion. Attackers can send unlimited POST requests to the authentication endpoint, causing unbounded growth of the challenge store file and excessive CPU and disk I/O through repeated JSON file rewrites.
{
"affected": [],
"aliases": [
"CVE-2026-49955"
],
"database_specific": {
"cwe_ids": [
"CWE-770"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2026-06-09T17:17:48Z",
"severity": "MODERATE"
},
"details": "Hermes WebUI before version 0.51.270 contains a resource exhaustion vulnerability that allows unauthenticated remote attackers to degrade service availability by repeatedly calling the passkey options endpoint without completing assertion. Attackers can send unlimited POST requests to the authentication endpoint, causing unbounded growth of the challenge store file and excessive CPU and disk I/O through repeated JSON file rewrites.",
"id": "GHSA-wwx5-jq7h-rp7v",
"modified": "2026-06-09T18:31:01Z",
"published": "2026-06-09T18:31:01Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-49955"
},
{
"type": "WEB",
"url": "https://github.com/nesquena/hermes-webui/pull/3624"
},
{
"type": "WEB",
"url": "https://github.com/nesquena/hermes-webui/pull/3674"
},
{
"type": "WEB",
"url": "https://github.com/nesquena/hermes-webui/commit/58528a4d88b0fa4f7b822e31d6051c669769bd3b"
},
{
"type": "WEB",
"url": "https://github.com/nesquena/hermes-webui/releases/tag/v0.51.270"
},
{
"type": "WEB",
"url": "https://www.vulncheck.com/advisories/hermes-webui-resource-exhaustion-via-passkey-options"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L",
"type": "CVSS_V3"
},
{
"score": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X",
"type": "CVSS_V4"
}
]
}
GHSA-WWX6-X28X-8259
Vulnerability from github – Published: 2026-05-29 19:37 – Updated: 2026-06-11 14:06Summary
When SSH compression is enabled, russh accepted compressed packets whose on-wire size passed the normal transport packet-length checks but whose decompressed size was much larger. This allowed a remote peer to send oversized post-decompression packets that should have been rejected.
In current releases, this is a remote denial-of-service / resource-exhaustion issue in the post-decompression receive path.
In older releases before 0.58.0, the same remote decompression path used CryptoVec, which appears to make the historical impact worse.
Details
The normal SSH transport read path enforces a packet-length limit before the packet body is read:
russh/src/cipher/mod.rs
However, RFC 4253 compression is applied to the SSH payload field only. The packet_length field and MAC are computed over the compressed payload, so a packet that is reasonably sized on the wire can still expand to a much larger message body after decompression.
In russh, compressed packet bodies are later decompressed in:
russh/src/compression.rsrussh/src/client/mod.rsrussh/src/server/session.rs
Before the fix, Decompress::decompress() grew its output buffer by repeated doubling and did not enforce a separate post-decompression ceiling. That meant a peer could send a small compressed packet that passed the normal on-wire transport length checks and then inflate it into a much larger packet after decompression.
It was verified that an attacker-crafted compressed payload can stay below the normal 256 KiB implementation transport packet cap while still inflating above the intended post-decompression bound. In other words, this is not only a "large on-wire packet" issue.
Version detail:
- The underlying post-decompression bounds bug appears to affect
russhas far back as0.34.0. - In historical releases
>= 0.34.0, < 0.58.0, the remote decompression path still usedCryptoVec. Remote compressed SSH traffic could drive that path, and under constrained memory that historical code path could abort the process. - In current-style releases
>= 0.58.0, non-secret packet/decompression buffers were moved offCryptoVecand ontoVec<u8>, but the post-decompression size still remained unbounded. So the bug class remained reachable remotely, but the maintained-line impact is a current remote DoS / oversized-packet-acceptance issue rather than the olderCryptoVec-based abort story. - The maintained-line fix was verified against
0.60.2.
Compression is not selected in a default-vs-default russh session because the default preference order puts none first. However, the default server configuration still advertises zlib and zlib@openssh.com, and server-side negotiation follows the client's preference order for common algorithms. A client that prefers compression can therefore negotiate it with a default russh server.
OpenSSH portable was checked at /home/mjc/projects/openssh-portable commit 45b30e0a5. OpenSSH enforces a 256 KiB transport packet cap before decompression, but it does not reuse that cap after decompression. Instead, decompression writes to an sshbuf, which is indirectly bounded by OpenSSH's SSHBUF_SIZE_MAX hard maximum of 0x8000000 bytes (128 MiB).
The patch direction should follow that model: add an explicit post-decompression ceiling of 128 MiB, rather than assuming the compressed transport packet cap also bounds decompressed payload size.
Relevant OpenSSH reference points:
/home/mjc/projects/openssh-portable/packet.c:PACKET_MAX_SIZE (256 * 1024)/home/mjc/projects/openssh-portable/packet.c:uncompress_buffer()inflates intocompression_buffer/home/mjc/projects/openssh-portable/sshbuf.h:SSHBUF_SIZE_MAX 0x8000000
RFC / OpenSSH Comparison
RFC 4253 section 6 defines the binary packet format:
packet_lengthpadding_lengthpayload- random padding
- MAC
RFC 4253 section 6.2 says that, when compression is negotiated, the payload field is compressed, and that packet_length and MAC are computed from the compressed payload. The RFC also says implementations should check that packet length is reasonable to avoid denial-of-service and buffer-overflow attacks.
That means the pre-decompression transport packet length check is necessary but not sufficient. A correct implementation still needs a reasonable bound on the decompressed payload that becomes parser input.
OpenSSH provides such a bound indirectly through sshbuf's hard maximum. The russh fix should make the corresponding post-decompression bound explicit.
PoC
There were two kinds of proof:
- a wire-cap sanity test showing an attacker-crafted best-compressed
DEBUGpayload can stay below the normal SSH transport packet cap while still inflating beyond the intended post-decompression bound - direct client and server receive-path tests that exercise the oversized post-decompression behavior itself
The current in-tree regression tests are:
tests::compress::oversized_debug_payload_can_stay_below_wire_capcompression::tests::oversized_decompressed_packet_is_rejectedclient::tests::compressed_debug_is_ignored_after_client_parses_itclient::tests::oversized_compressed_debug_is_rejected_before_client_ignores_itserver::session::tests::compressed_debug_is_ignored_after_server_parses_itserver::session::tests::oversized_compressed_debug_is_rejected_before_server_ignores_it
The important behavior is:
- An attacker-crafted best-compressed
DEBUGpayload can stay below the normal256 KiBtransport packet cap while still inflating beyond128 MiB. - In the direct client and server receive paths, small compressed
DEBUGpackets are still ignored normally after parsing. - In the direct client and server receive paths, oversized compressed
DEBUGpackets are rejected before the implementation reaches the normal "ignore DEBUG" behavior.
The strongest PoC for severity is the unauthenticated server-side case. A malicious client can choose zlib in the initial key exchange, because the default server advertises it and server-side negotiation follows the client's preference order for common algorithms. After NEWKEYS, but before authentication, the client can send a transport-layer SSH_MSG_DEBUG packet whose compressed body is below the transport packet cap but whose decompressed body exceeds the post-decompression cap.
That demonstrates the AV:N/AC:L/PR:N/UI:N case directly: the attacker is a remote SSH client and does not need a successfully authenticated session.
fn compressed_debug_payload(payload_len: usize) -> Vec<u8> {
let mut payload = vec![b'A'; payload_len];
payload[0] = crate::msg::DEBUG;
let mut encoder =
flate2::write::ZlibEncoder::new(Vec::new(), flate2::Compression::best());
encoder.write_all(&payload).unwrap();
let compressed = encoder.finish().unwrap();
assert!(
compressed.len() < 256 * 1024,
"oversized post-decompression payload still fits under the wire cap"
);
compressed
}
fn incoming_packet(compressed: Vec<u8>) -> SSHBuffer {
let mut buffer = SSHBuffer::new();
// maybe_decompress() receives the clear SSHBuffer after packet framing,
// and decompresses bytes after packet_length + padding_length.
buffer.buffer.extend_from_slice(&[0; 5]);
buffer.buffer.extend_from_slice(&compressed);
buffer
}
#[test]
fn unauthenticated_client_zlib_debug_is_rejected_by_server_before_auth() {
let mut server = preauth_server_session_after_newkeys_with_zlib_decompressor();
let oversized = MAXIMUM_DECOMPRESSED_PACKET_LEN + 1024;
let buffer = incoming_packet(compressed_debug_payload(oversized));
let err = server.maybe_decompress(&buffer).unwrap_err();
assert!(
matches!(err, crate::Error::PacketSize(len) if len > MAXIMUM_DECOMPRESSED_PACKET_LEN)
);
}
The equivalent wire-level attack shape is:
1. Connect to a russh server using the default compression advertisement.
2. Send SSH_MSG_KEXINIT with compression client-to-server preference:
zlib,zlib@openssh.com,none
3. Complete key exchange and send SSH_MSG_NEWKEYS.
4. Before any SSH_MSG_USERAUTH_REQUEST, send a compressed SSH_MSG_DEBUG packet:
- compressed packet body: < 256 KiB
- decompressed packet body: > 128 MiB
5. Vulnerable behavior: russh accepts and inflates the packet, then reaches the
normal DEBUG ignore path.
6. Fixed behavior: russh rejects during decompression with Error::PacketSize.
The direct receive-path client/server regression tests are still useful because they isolate the bug precisely. They construct the post-decryption compressed packet body passed to maybe_decompress() and prove that the oversized packet is rejected before normal DEBUG ignore handling. The server-side pre-auth variant above is the one that justifies the highest CVSS framing for this bug.
The most important targeted checks are:
cargo test -p russh oversized_debug_payload_can_stay_below_wire_cap -- --nocapture
cargo test -p russh oversized_compressed_debug_is_rejected_before_client_ignores_it -- --nocapture
cargo test -p russh oversized_compressed_debug_is_rejected_before_server_ignores_it -- --nocapture
Before the fix, both the direct client and direct server receive-path oversized checks went red because the compressed payload was accepted and decompressed instead of being rejected at the post-decompression boundary. After the fix, they pass.
Impact
Suggested CVSS v3.1 for current maintained releases:
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H- Score:
7.5
Reasoning:
AV:N: reachable by a remote SSH peerAC:L: straightforward once compression is enabledPR:N,UI:N: no prior auth or user interaction requiredC:N,I:N: confidentiality or integrity impact was not demonstratedA:H: remote peer can cause oversized post-decompression packet processing and disconnect / denial of service
Affected versions:
- historical stronger case:
russh >= 0.34.0, < 0.58.0 - current maintained remote DoS case:
russh >= 0.58.0, including0.60.3
Fix / Patch Direction
Add an explicit maximum decompressed SSH packet size and enforce it inside Decompress::decompress() before returning decompressed bytes to the client or server packet parser.
The intended ceiling is 128 MiB, matching OpenSSH portable's effective sshbuf hard maximum for post-decompression packet storage. The fix should reject decompression output larger than that bound with a packet-size error before normal message dispatch.
The fix should preserve normal compressed packet behavior below the cap, including DEBUG packets that are decompressed and then ignored through the existing normal path.
Patch branch:
fix/zlib-decompression-cap
{
"affected": [
{
"package": {
"ecosystem": "crates.io",
"name": "russh"
},
"ranges": [
{
"events": [
{
"introduced": "0.34.0"
},
{
"fixed": "0.61.1"
}
],
"type": "ECOSYSTEM"
}
]
}
],
"aliases": [
"CVE-2026-46702"
],
"database_specific": {
"cwe_ids": [
"CWE-770"
],
"github_reviewed": true,
"github_reviewed_at": "2026-05-29T19:37:14Z",
"nvd_published_at": "2026-06-10T22:17:00Z",
"severity": "HIGH"
},
"details": "### Summary\n\nWhen SSH compression is enabled, `russh` accepted compressed packets whose on-wire size passed the normal transport packet-length checks but whose decompressed size was much larger. This allowed a remote peer to send oversized post-decompression packets that should have been rejected.\n\nIn current releases, this is a remote denial-of-service / resource-exhaustion issue in the post-decompression receive path.\n\nIn older releases before `0.58.0`, the same remote decompression path used `CryptoVec`, which appears to make the historical impact worse.\n\n### Details\n\nThe normal SSH transport read path enforces a packet-length limit before the packet body is read:\n\n- `russh/src/cipher/mod.rs`\n\nHowever, RFC 4253 compression is applied to the SSH `payload` field only. The `packet_length` field and MAC are computed over the compressed payload, so a packet that is reasonably sized on the wire can still expand to a much larger message body after decompression.\n\nIn `russh`, compressed packet bodies are later decompressed in:\n\n- `russh/src/compression.rs`\n- `russh/src/client/mod.rs`\n- `russh/src/server/session.rs`\n\nBefore the fix, `Decompress::decompress()` grew its output buffer by repeated doubling and did not enforce a separate post-decompression ceiling. That meant a peer could send a small compressed packet that passed the normal on-wire transport length checks and then inflate it into a much larger packet after decompression.\n\nIt was verified that an attacker-crafted compressed payload can stay below the normal `256 KiB` implementation transport packet cap while still inflating above the intended post-decompression bound. In other words, this is not only a \"large on-wire packet\" issue.\n\nVersion detail:\n\n- The underlying post-decompression bounds bug appears to affect `russh` as far back as `0.34.0`.\n- In historical releases `\u003e= 0.34.0, \u003c 0.58.0`, the remote decompression path still used `CryptoVec`. Remote compressed SSH traffic could drive that path, and under constrained memory that historical code path could abort the process.\n- In current-style releases `\u003e= 0.58.0`, non-secret packet/decompression buffers were moved off `CryptoVec` and onto `Vec\u003cu8\u003e`, but the post-decompression size still remained unbounded. So the bug class remained reachable remotely, but the maintained-line impact is a current remote DoS / oversized-packet-acceptance issue rather than the older `CryptoVec`-based abort story.\n- The maintained-line fix was verified against `0.60.2`.\n\nCompression is not selected in a default-vs-default `russh` session because the default preference order puts `none` first. However, the default server configuration still advertises `zlib` and `zlib@openssh.com`, and server-side negotiation follows the client\u0027s preference order for common algorithms. A client that prefers compression can therefore negotiate it with a default `russh` server.\n\nOpenSSH portable was checked at `/home/mjc/projects/openssh-portable` commit `45b30e0a5`. OpenSSH enforces a `256 KiB` transport packet cap before decompression, but it does not reuse that cap after decompression. Instead, decompression writes to an `sshbuf`, which is indirectly bounded by OpenSSH\u0027s `SSHBUF_SIZE_MAX` hard maximum of `0x8000000` bytes (`128 MiB`).\n\nThe patch direction should follow that model: add an explicit post-decompression ceiling of `128 MiB`, rather than assuming the compressed transport packet cap also bounds decompressed payload size.\n\nRelevant OpenSSH reference points:\n\n- `/home/mjc/projects/openssh-portable/packet.c`: `PACKET_MAX_SIZE (256 * 1024)`\n- `/home/mjc/projects/openssh-portable/packet.c`: `uncompress_buffer()` inflates into `compression_buffer`\n- `/home/mjc/projects/openssh-portable/sshbuf.h`: `SSHBUF_SIZE_MAX 0x8000000`\n\n### RFC / OpenSSH Comparison\n\nRFC 4253 section 6 defines the binary packet format:\n\n- `packet_length`\n- `padding_length`\n- `payload`\n- random padding\n- MAC\n\nRFC 4253 section 6.2 says that, when compression is negotiated, the `payload` field is compressed, and that `packet_length` and MAC are computed from the compressed payload. The RFC also says implementations should check that packet length is reasonable to avoid denial-of-service and buffer-overflow attacks.\n\nThat means the pre-decompression transport packet length check is necessary but not sufficient. A correct implementation still needs a reasonable bound on the decompressed payload that becomes parser input.\n\nOpenSSH provides such a bound indirectly through `sshbuf`\u0027s hard maximum. The `russh` fix should make the corresponding post-decompression bound explicit.\n\n### PoC\n\nThere were two kinds of proof:\n\n- a wire-cap sanity test showing an attacker-crafted best-compressed `DEBUG` payload can stay below the normal SSH transport packet cap while still inflating beyond the intended post-decompression bound\n- direct client and server receive-path tests that exercise the oversized post-decompression behavior itself\n\nThe current in-tree regression tests are:\n\n- `tests::compress::oversized_debug_payload_can_stay_below_wire_cap`\n- `compression::tests::oversized_decompressed_packet_is_rejected`\n- `client::tests::compressed_debug_is_ignored_after_client_parses_it`\n- `client::tests::oversized_compressed_debug_is_rejected_before_client_ignores_it`\n- `server::session::tests::compressed_debug_is_ignored_after_server_parses_it`\n- `server::session::tests::oversized_compressed_debug_is_rejected_before_server_ignores_it`\n\nThe important behavior is:\n\n1. An attacker-crafted best-compressed `DEBUG` payload can stay below the normal `256 KiB` transport packet cap while still inflating beyond `128 MiB`.\n2. In the direct client and server receive paths, small compressed `DEBUG` packets are still ignored normally after parsing.\n3. In the direct client and server receive paths, oversized compressed `DEBUG` packets are rejected before the implementation reaches the normal \"ignore DEBUG\" behavior.\n\nThe strongest PoC for severity is the unauthenticated server-side case. A malicious client can choose `zlib` in the initial key exchange, because the default server advertises it and server-side negotiation follows the client\u0027s preference order for common algorithms. After `NEWKEYS`, but before authentication, the client can send a transport-layer `SSH_MSG_DEBUG` packet whose compressed body is below the transport packet cap but whose decompressed body exceeds the post-decompression cap.\n\nThat demonstrates the `AV:N/AC:L/PR:N/UI:N` case directly: the attacker is a remote SSH client and does not need a successfully authenticated session.\n\n```rust\nfn compressed_debug_payload(payload_len: usize) -\u003e Vec\u003cu8\u003e {\n let mut payload = vec![b\u0027A\u0027; payload_len];\n payload[0] = crate::msg::DEBUG;\n\n let mut encoder =\n flate2::write::ZlibEncoder::new(Vec::new(), flate2::Compression::best());\n encoder.write_all(\u0026payload).unwrap();\n let compressed = encoder.finish().unwrap();\n\n assert!(\n compressed.len() \u003c 256 * 1024,\n \"oversized post-decompression payload still fits under the wire cap\"\n );\n compressed\n}\n\nfn incoming_packet(compressed: Vec\u003cu8\u003e) -\u003e SSHBuffer {\n let mut buffer = SSHBuffer::new();\n // maybe_decompress() receives the clear SSHBuffer after packet framing,\n // and decompresses bytes after packet_length + padding_length.\n buffer.buffer.extend_from_slice(\u0026[0; 5]);\n buffer.buffer.extend_from_slice(\u0026compressed);\n buffer\n}\n\n#[test]\nfn unauthenticated_client_zlib_debug_is_rejected_by_server_before_auth() {\n let mut server = preauth_server_session_after_newkeys_with_zlib_decompressor();\n let oversized = MAXIMUM_DECOMPRESSED_PACKET_LEN + 1024;\n let buffer = incoming_packet(compressed_debug_payload(oversized));\n\n let err = server.maybe_decompress(\u0026buffer).unwrap_err();\n assert!(\n matches!(err, crate::Error::PacketSize(len) if len \u003e MAXIMUM_DECOMPRESSED_PACKET_LEN)\n );\n}\n```\n\nThe equivalent wire-level attack shape is:\n\n```text\n1. Connect to a russh server using the default compression advertisement.\n2. Send SSH_MSG_KEXINIT with compression client-to-server preference:\n zlib,zlib@openssh.com,none\n3. Complete key exchange and send SSH_MSG_NEWKEYS.\n4. Before any SSH_MSG_USERAUTH_REQUEST, send a compressed SSH_MSG_DEBUG packet:\n - compressed packet body: \u003c 256 KiB\n - decompressed packet body: \u003e 128 MiB\n5. Vulnerable behavior: russh accepts and inflates the packet, then reaches the\n normal DEBUG ignore path.\n6. Fixed behavior: russh rejects during decompression with Error::PacketSize.\n```\n\nThe direct receive-path client/server regression tests are still useful because they isolate the bug precisely. They construct the post-decryption compressed packet body passed to `maybe_decompress()` and prove that the oversized packet is rejected before normal `DEBUG` ignore handling. The server-side pre-auth variant above is the one that justifies the highest CVSS framing for this bug.\n\nThe most important targeted checks are:\n\n```bash\ncargo test -p russh oversized_debug_payload_can_stay_below_wire_cap -- --nocapture\ncargo test -p russh oversized_compressed_debug_is_rejected_before_client_ignores_it -- --nocapture\ncargo test -p russh oversized_compressed_debug_is_rejected_before_server_ignores_it -- --nocapture\n```\n\nBefore the fix, both the direct client and direct server receive-path oversized checks went red because the compressed payload was accepted and decompressed instead of being rejected at the post-decompression boundary. After the fix, they pass.\n\n### Impact\n\nSuggested CVSS v3.1 for current maintained releases:\n\n- `CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H`\n- Score: `7.5`\n\nReasoning:\n\n- `AV:N`: reachable by a remote SSH peer\n- `AC:L`: straightforward once compression is enabled\n- `PR:N`, `UI:N`: no prior auth or user interaction required\n- `C:N`, `I:N`: confidentiality or integrity impact was not demonstrated\n- `A:H`: remote peer can cause oversized post-decompression packet processing and disconnect / denial of service\n\nAffected versions:\n\n- historical stronger case: `russh \u003e= 0.34.0, \u003c 0.58.0`\n- current maintained remote DoS case: `russh \u003e= 0.58.0`, including `0.60.3`\n\n### Fix / Patch Direction\n\nAdd an explicit maximum decompressed SSH packet size and enforce it inside `Decompress::decompress()` before returning decompressed bytes to the client or server packet parser.\n\nThe intended ceiling is `128 MiB`, matching OpenSSH portable\u0027s effective `sshbuf` hard maximum for post-decompression packet storage. The fix should reject decompression output larger than that bound with a packet-size error before normal message dispatch.\n\nThe fix should preserve normal compressed packet behavior below the cap, including `DEBUG` packets that are decompressed and then ignored through the existing normal path.\n\nPatch branch:\n\n```text\nfix/zlib-decompression-cap\n```",
"id": "GHSA-wwx6-x28x-8259",
"modified": "2026-06-11T14:06:26Z",
"published": "2026-05-29T19:37:14Z",
"references": [
{
"type": "WEB",
"url": "https://github.com/Eugeny/russh/security/advisories/GHSA-wwx6-x28x-8259"
},
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-46702"
},
{
"type": "PACKAGE",
"url": "https://github.com/Eugeny/russh"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
"type": "CVSS_V3"
}
],
"summary": "russh: Post-decompression SSH packet size was not bounded, allowing remote oversized compressed packets"
}
Mitigation
Clearly specify the minimum and maximum expectations for capabilities, and dictate which behaviors are acceptable when resource allocation reaches limits.
Mitigation
Limit the amount of resources that are accessible to unprivileged users. Set per-user limits for resources. Allow the system administrator to define these limits. Be careful to avoid CWE-410.
Mitigation
Design throttling mechanisms into the system architecture. The best protection is to limit the amount of resources that an unauthorized user can cause to be expended. A strong authentication and access control model will help prevent such attacks from occurring in the first place, and it will help the administrator to identify who is committing the abuse. The login application should be protected against DoS attacks as much as possible. Limiting the database access, perhaps by caching result sets, can help minimize the resources expended. To further limit the potential for a DoS attack, consider tracking the rate of requests received from users and blocking requests that exceed a defined rate threshold.
Mitigation MIT-5
Strategy: Input Validation
- Assume all input is malicious. Use an "accept known good" input validation strategy, i.e., use a list of acceptable inputs that strictly conform to specifications. Reject any input that does not strictly conform to specifications, or transform it into something that does.
- When performing input validation, consider all potentially relevant properties, including length, type of input, the full range of acceptable values, missing or extra inputs, syntax, consistency across related fields, and conformance to business rules. As an example of business rule logic, "boat" may be syntactically valid because it only contains alphanumeric characters, but it is not valid if the input is only expected to contain colors such as "red" or "blue."
- Do not rely exclusively on looking for malicious or malformed inputs. This is likely to miss at least one undesirable input, especially if the code's environment changes. This can give attackers enough room to bypass the intended validation. However, denylists can be useful for detecting potential attacks or determining which inputs are so malformed that they should be rejected outright.
Mitigation MIT-15
For any security checks that are performed on the client side, ensure that these checks are duplicated on the server side, in order to avoid CWE-602. Attackers can bypass the client-side checks by modifying values after the checks have been performed, or by changing the client to remove the client-side checks entirely. Then, these modified values would be submitted to the server.
Mitigation
- Mitigation of resource exhaustion attacks requires that the target system either:
- The first of these solutions is an issue in itself though, since it may allow attackers to prevent the use of the system by a particular valid user. If the attacker impersonates the valid user, they may be able to prevent the user from accessing the server in question.
- The second solution can be difficult to effectively institute -- and even when properly done, it does not provide a full solution. It simply requires more resources on the part of the attacker.
- recognizes the attack and denies that user further access for a given amount of time, typically by using increasing time delays
- uniformly throttles all requests in order to make it more difficult to consume resources more quickly than they can again be freed.
Mitigation
Ensure that protocols have specific limits of scale placed on them.
Mitigation MIT-38.1
- If the program must fail, ensure that it fails gracefully (fails closed). There may be a temptation to simply let the program fail poorly in cases such as low memory conditions, but an attacker may be able to assert control before the software has fully exited. Alternately, an uncontrolled failure could cause cascading problems with other downstream components; for example, the program could send a signal to a downstream process so the process immediately knows that a problem has occurred and has a better chance of recovery.
- Ensure that all failures in resource allocation place the system into a safe posture.
Mitigation MIT-47
Strategy: Resource Limitation
- Use quotas or other resource-limiting settings provided by the operating system or environment. For example, when managing system resources in POSIX, setrlimit() can be used to set limits for certain types of resources, and getrlimit() can determine how many resources are available. However, these functions are not available on all operating systems.
- When the current levels get close to the maximum that is defined for the application (see CWE-770), then limit the allocation of further resources to privileged users; alternately, begin releasing resources for less-privileged users. While this mitigation may protect the system from attack, it will not necessarily stop attackers from adversely impacting other users.
- Ensure that the application performs the appropriate error checks and error handling in case resources become unavailable (CWE-703).
CAPEC-125: Flooding
An adversary consumes the resources of a target by rapidly engaging in a large number of interactions with the target. This type of attack generally exposes a weakness in rate limiting or flow. When successful this attack prevents legitimate users from accessing the service and can cause the target to crash. This attack differs from resource depletion through leaks or allocations in that the latter attacks do not rely on the volume of requests made to the target but instead focus on manipulation of the target's operations. The key factor in a flooding attack is the number of requests the adversary can make in a given period of time. The greater this number, the more likely an attack is to succeed against a given target.
CAPEC-130: Excessive Allocation
An adversary causes the target to allocate excessive resources to servicing the attackers' request, thereby reducing the resources available for legitimate services and degrading or denying services. Usually, this attack focuses on memory allocation, but any finite resource on the target could be the attacked, including bandwidth, processing cycles, or other resources. This attack does not attempt to force this allocation through a large number of requests (that would be Resource Depletion through Flooding) but instead uses one or a small number of requests that are carefully formatted to force the target to allocate excessive resources to service this request(s). Often this attack takes advantage of a bug in the target to cause the target to allocate resources vastly beyond what would be needed for a normal request.
CAPEC-147: XML Ping of the Death
An attacker initiates a resource depletion attack where a large number of small XML messages are delivered at a sufficiently rapid rate to cause a denial of service or crash of the target. Transactions such as repetitive SOAP transactions can deplete resources faster than a simple flooding attack because of the additional resources used by the SOAP protocol and the resources necessary to process SOAP messages. The transactions used are immaterial as long as they cause resource utilization on the target. In other words, this is a normal flooding attack augmented by using messages that will require extra processing on the target.
CAPEC-197: Exponential Data Expansion
An adversary submits data to a target application which contains nested exponential data expansion to produce excessively large output. Many data format languages allow the definition of macro-like structures that can be used to simplify the creation of complex structures. However, this capability can be abused to create excessive demands on a processor's CPU and memory. A small number of nested expansions can result in an exponential growth in demands on memory.
CAPEC-229: Serialized Data Parameter Blowup
This attack exploits certain serialized data parsers (e.g., XML, YAML, etc.) which manage data in an inefficient manner. The attacker crafts an serialized data file with multiple configuration parameters in the same dataset. In a vulnerable parser, this results in a denial of service condition where CPU resources are exhausted because of the parsing algorithm. The weakness being exploited is tied to parser implementation and not language specific.
CAPEC-230: Serialized Data with Nested Payloads
Applications often need to transform data in and out of a data format (e.g., XML and YAML) by using a parser. It may be possible for an adversary to inject data that may have an adverse effect on the parser when it is being processed. Many data format languages allow the definition of macro-like structures that can be used to simplify the creation of complex structures. By nesting these structures, causing the data to be repeatedly substituted, an adversary can cause the parser to consume more resources while processing, causing excessive memory consumption and CPU utilization.
CAPEC-231: Oversized Serialized Data Payloads
An adversary injects oversized serialized data payloads into a parser during data processing to produce adverse effects upon the parser such as exhausting system resources and arbitrary code execution.
CAPEC-469: HTTP DoS
An attacker performs flooding at the HTTP level to bring down only a particular web application rather than anything listening on a TCP/IP connection. This denial of service attack requires substantially fewer packets to be sent which makes DoS harder to detect. This is an equivalent of SYN flood in HTTP. The idea is to keep the HTTP session alive indefinitely and then repeat that hundreds of times. This attack targets resource depletion weaknesses in web server software. The web server will wait to attacker's responses on the initiated HTTP sessions while the connection threads are being exhausted.
CAPEC-482: TCP Flood
An adversary may execute a flooding attack using the TCP protocol with the intent to deny legitimate users access to a service. These attacks exploit the weakness within the TCP protocol where there is some state information for the connection the server needs to maintain. This often involves the use of TCP SYN messages.
CAPEC-486: UDP Flood
An adversary may execute a flooding attack using the UDP protocol with the intent to deny legitimate users access to a service by consuming the available network bandwidth. Additionally, firewalls often open a port for each UDP connection destined for a service with an open UDP port, meaning the firewalls in essence save the connection state thus the high packet nature of a UDP flood can also overwhelm resources allocated to the firewall. UDP attacks can also target services like DNS or VoIP which utilize these protocols. Additionally, due to the session-less nature of the UDP protocol, the source of a packet is easily spoofed making it difficult to find the source of the attack.
CAPEC-487: ICMP Flood
An adversary may execute a flooding attack using the ICMP protocol with the intent to deny legitimate users access to a service by consuming the available network bandwidth. A typical attack involves a victim server receiving ICMP packets at a high rate from a wide range of source addresses. Additionally, due to the session-less nature of the ICMP protocol, the source of a packet is easily spoofed making it difficult to find the source of the attack.
CAPEC-488: HTTP Flood
An adversary may execute a flooding attack using the HTTP protocol with the intent to deny legitimate users access to a service by consuming resources at the application layer such as web services and their infrastructure. These attacks use legitimate session-based HTTP GET requests designed to consume large amounts of a server's resources. Since these are legitimate sessions this attack is very difficult to detect.
CAPEC-489: SSL Flood
An adversary may execute a flooding attack using the SSL protocol with the intent to deny legitimate users access to a service by consuming all the available resources on the server side. These attacks take advantage of the asymmetric relationship between the processing power used by the client and the processing power used by the server to create a secure connection. In this manner the attacker can make a large number of HTTPS requests on a low provisioned machine to tie up a disproportionately large number of resources on the server. The clients then continue to keep renegotiating the SSL connection. When multiplied by a large number of attacking machines, this attack can result in a crash or loss of service to legitimate users.
CAPEC-490: Amplification
An adversary may execute an amplification where the size of a response is far greater than that of the request that generates it. The goal of this attack is to use a relatively few resources to create a large amount of traffic against a target server. To execute this attack, an adversary send a request to a 3rd party service, spoofing the source address to be that of the target server. The larger response that is generated by the 3rd party service is then sent to the target server. By sending a large number of initial requests, the adversary can generate a tremendous amount of traffic directed at the target. The greater the discrepancy in size between the initial request and the final payload delivered to the target increased the effectiveness of this attack.
CAPEC-491: Quadratic Data Expansion
An adversary exploits macro-like substitution to cause a denial of service situation due to excessive memory being allocated to fully expand the data. The result of this denial of service could cause the application to freeze or crash. This involves defining a very large entity and using it multiple times in a single entity substitution. CAPEC-197 is a similar attack pattern, but it is easier to discover and defend against. This attack pattern does not perform multi-level substitution and therefore does not obviously appear to consume extensive resources.
CAPEC-493: SOAP Array Blowup
An adversary may execute an attack on a web service that uses SOAP messages in communication. By sending a very large SOAP array declaration to the web service, the attacker forces the web service to allocate space for the array elements before they are parsed by the XML parser. The attacker message is typically small in size containing a large array declaration of say 1,000,000 elements and a couple of array elements. This attack targets exhaustion of the memory resources of the web service.
CAPEC-494: TCP Fragmentation
An adversary may execute a TCP Fragmentation attack against a target with the intention of avoiding filtering rules of network controls, by attempting to fragment the TCP packet such that the headers flag field is pushed into the second fragment which typically is not filtered.
CAPEC-495: UDP Fragmentation
An attacker may execute a UDP Fragmentation attack against a target server in an attempt to consume resources such as bandwidth and CPU. IP fragmentation occurs when an IP datagram is larger than the MTU of the route the datagram has to traverse. Typically the attacker will use large UDP packets over 1500 bytes of data which forces fragmentation as ethernet MTU is 1500 bytes. This attack is a variation on a typical UDP flood but it enables more network bandwidth to be consumed with fewer packets. Additionally it has the potential to consume server CPU resources and fill memory buffers associated with the processing and reassembling of fragmented packets.
CAPEC-496: ICMP Fragmentation
An attacker may execute a ICMP Fragmentation attack against a target with the intention of consuming resources or causing a crash. The attacker crafts a large number of identical fragmented IP packets containing a portion of a fragmented ICMP message. The attacker these sends these messages to a target host which causes the host to become non-responsive. Another vector may be sending a fragmented ICMP message to a target host with incorrect sizes in the header which causes the host to hang.
CAPEC-528: XML Flood
An adversary may execute a flooding attack using XML messages with the intent to deny legitimate users access to a web service. These attacks are accomplished by sending a large number of XML based requests and letting the service attempt to parse each one. In many cases this type of an attack will result in a XML Denial of Service (XDoS) due to an application becoming unstable, freezing, or crashing.