CWE-22
Allowed-with-ReviewImproper Limitation of a Pathname to a Restricted Directory ('Path Traversal')
Abstraction: Base · Status: Stable
The product uses external input to construct a pathname that is intended to identify a file or directory that is located underneath a restricted parent directory, but the product does not properly neutralize special elements within the pathname that can cause the pathname to resolve to a location that is outside of the restricted directory.
13064 vulnerabilities reference this CWE, most recent first.
GHSA-WXG2-RRF5-G5RR
Vulnerability from github – Published: 2022-05-02 03:28 – Updated: 2022-05-02 03:28Directory traversal vulnerability in download.php in Rama Zaiten CMS 0.9.8 and earlier allows remote attackers to read arbitrary files via a .. (dot dot) in the file parameter.
{
"affected": [],
"aliases": [
"CVE-2009-1768"
],
"database_specific": {
"cwe_ids": [
"CWE-22"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2009-05-22T18:30:00Z",
"severity": "MODERATE"
},
"details": "Directory traversal vulnerability in download.php in Rama Zaiten CMS 0.9.8 and earlier allows remote attackers to read arbitrary files via a .. (dot dot) in the file parameter.",
"id": "GHSA-wxg2-rrf5-g5rr",
"modified": "2022-05-02T03:28:20Z",
"published": "2022-05-02T03:28:20Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2009-1768"
},
{
"type": "WEB",
"url": "https://exchange.xforce.ibmcloud.com/vulnerabilities/50572"
},
{
"type": "WEB",
"url": "https://www.exploit-db.com/exploits/8700"
},
{
"type": "WEB",
"url": "http://osvdb.org/54546"
},
{
"type": "WEB",
"url": "http://secunia.com/advisories/35116"
},
{
"type": "WEB",
"url": "http://www.securityfocus.com/bid/34995"
},
{
"type": "WEB",
"url": "http://www.vupen.com/english/advisories/2009/1343"
}
],
"schema_version": "1.4.0",
"severity": []
}
GHSA-WXHM-2MQ7-7697
Vulnerability from github – Published: 2026-07-17 19:46 – Updated: 2026-07-17 19:46Summary
Prompty loaders expanded ${file:...} references in .prompty frontmatter without enforcing that the resolved path stayed within an authorized directory. An attacker-controlled prompt file could use path traversal or an absolute path to cause the host application to read files accessible to the process.
Affected packages
- PyPI
promptyversions<= 2.0.0b1; fixed in2.0.0b2 - npm
@prompty/coreversions<= 2.0.0-beta.1; fixed in2.0.0-beta.2 - crates.io
promptyversions<= 2.0.0-beta.1; fixed in2.0.0-beta.2 - NuGet
Prompty.Coreversions<= 2.0.0-beta.1; fixed in2.0.0-beta.2
Impact
Applications that load untrusted .prompty files, user-provided prompt paths, or prompt bundles from less-trusted locations could disclose local files available to the application process when expanded values are logged, returned, or otherwise exposed.
Remediation
Upgrade to the fixed runtime version for your ecosystem. The fix makes file references secure by default: ${file:...} may only resolve within the directory tree containing the .prompty file. Host applications that need shared prompt assets outside that tree must explicitly provide allowed file roots through runtime load options. Absolute paths, .. traversal, and symlink escapes outside allowed roots are rejected.
Fix details
The patched runtimes canonicalize file-reference targets and allowed roots before reading referenced files, reject targets outside the prompt directory by default, and add regression coverage for traversal, absolute paths, explicit allowlists, and symlink escapes. The release commit is 88ac9948d7d37995edbb2f6d36913436626c39e1.
{
"affected": [
{
"database_specific": {
"last_known_affected_version_range": "\u003c= 2.0.0b1"
},
"package": {
"ecosystem": "PyPI",
"name": "prompty"
},
"ranges": [
{
"events": [
{
"introduced": "0"
},
{
"fixed": "2.0.0b2"
}
],
"type": "ECOSYSTEM"
}
]
},
{
"database_specific": {
"last_known_affected_version_range": "\u003c= 2.0.0-beta.1"
},
"package": {
"ecosystem": "npm",
"name": "@prompty/core"
},
"ranges": [
{
"events": [
{
"introduced": "0"
},
{
"fixed": "2.0.0-beta.2"
}
],
"type": "ECOSYSTEM"
}
]
},
{
"database_specific": {
"last_known_affected_version_range": "\u003c= 2.0.0-beta.1"
},
"package": {
"ecosystem": "crates.io",
"name": "prompty"
},
"ranges": [
{
"events": [
{
"introduced": "0"
},
{
"fixed": "2.0.0-beta.2"
}
],
"type": "ECOSYSTEM"
}
]
},
{
"database_specific": {
"last_known_affected_version_range": "\u003c= 2.0.0-beta.1"
},
"package": {
"ecosystem": "NuGet",
"name": "Prompty.Core"
},
"ranges": [
{
"events": [
{
"introduced": "0"
},
{
"fixed": "2.0.0-beta.2"
}
],
"type": "ECOSYSTEM"
}
]
}
],
"aliases": [
"CVE-2026-53598"
],
"database_specific": {
"cwe_ids": [
"CWE-22",
"CWE-200"
],
"github_reviewed": true,
"github_reviewed_at": "2026-07-17T19:46:05Z",
"nvd_published_at": "2026-07-16T16:19:12Z",
"severity": "HIGH"
},
"details": "## Summary\nPrompty loaders expanded `${file:...}` references in `.prompty` frontmatter without enforcing that the resolved path stayed within an authorized directory. An attacker-controlled prompt file could use path traversal or an absolute path to cause the host application to read files accessible to the process.\n\n## Affected packages\n- PyPI `prompty` versions `\u003c= 2.0.0b1`; fixed in `2.0.0b2`\n- npm `@prompty/core` versions `\u003c= 2.0.0-beta.1`; fixed in `2.0.0-beta.2`\n- crates.io `prompty` versions `\u003c= 2.0.0-beta.1`; fixed in `2.0.0-beta.2`\n- NuGet `Prompty.Core` versions `\u003c= 2.0.0-beta.1`; fixed in `2.0.0-beta.2`\n\n## Impact\nApplications that load untrusted `.prompty` files, user-provided prompt paths, or prompt bundles from less-trusted locations could disclose local files available to the application process when expanded values are logged, returned, or otherwise exposed.\n\n## Remediation\nUpgrade to the fixed runtime version for your ecosystem. The fix makes file references secure by default: `${file:...}` may only resolve within the directory tree containing the `.prompty` file. Host applications that need shared prompt assets outside that tree must explicitly provide allowed file roots through runtime load options. Absolute paths, `..` traversal, and symlink escapes outside allowed roots are rejected.\n\n## Fix details\nThe patched runtimes canonicalize file-reference targets and allowed roots before reading referenced files, reject targets outside the prompt directory by default, and add regression coverage for traversal, absolute paths, explicit allowlists, and symlink escapes. The release commit is `88ac9948d7d37995edbb2f6d36913436626c39e1`.",
"id": "GHSA-wxhm-2mq7-7697",
"modified": "2026-07-17T19:46:05Z",
"published": "2026-07-17T19:46:05Z",
"references": [
{
"type": "WEB",
"url": "https://github.com/microsoft/prompty/security/advisories/GHSA-wxhm-2mq7-7697"
},
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-53598"
},
{
"type": "WEB",
"url": "https://github.com/microsoft/prompty/commit/88ac9948d7d37995edbb2f6d36913436626c39e1"
},
{
"type": "PACKAGE",
"url": "https://github.com/microsoft/prompty"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N",
"type": "CVSS_V3"
}
],
"summary": "Prompty: Arbitrary file read via file reference expansion"
}
GHSA-WXJJ-JH24-CX5F
Vulnerability from github – Published: 2022-05-13 01:33 – Updated: 2022-05-13 01:33pcs before version 0.9.164 and 0.10 is vulnerable to a privilege escalation via authorized user malicious REST call. The REST interface of the pcsd service did not properly sanitize the file name from the /remote/put_file query. If the /etc/booth directory exists, an authenticated attacker with write permissions could create or overwrite arbitrary files with arbitrary data outside of the /etc/booth directory, in the context of the pcsd process.
{
"affected": [],
"aliases": [
"CVE-2018-1079"
],
"database_specific": {
"cwe_ids": [
"CWE-22"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2018-04-12T17:29:00Z",
"severity": "MODERATE"
},
"details": "pcs before version 0.9.164 and 0.10 is vulnerable to a privilege escalation via authorized user malicious REST call. The REST interface of the pcsd service did not properly sanitize the file name from the /remote/put_file query. If the /etc/booth directory exists, an authenticated attacker with write permissions could create or overwrite arbitrary files with arbitrary data outside of the /etc/booth directory, in the context of the pcsd process.",
"id": "GHSA-wxjj-jh24-cx5f",
"modified": "2022-05-13T01:33:33Z",
"published": "2022-05-13T01:33:33Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2018-1079"
},
{
"type": "WEB",
"url": "https://access.redhat.com/errata/RHSA-2018:1060"
},
{
"type": "WEB",
"url": "https://bugzilla.redhat.com/show_bug.cgi?id=CVE-2018-1079"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.0/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:N",
"type": "CVSS_V3"
}
]
}
GHSA-WXQ4-CC2Q-338Q
Vulnerability from github – Published: 2026-06-11 20:28 – Updated: 2026-06-11 20:28Impact
WsgiDAV 4.3.3 can allow a WebDAV request path containing an encoded parent-directory segment to escape the configured filesystem share root in a specific path layout.
Patches
The issue is fixed with version 4.3.4.
Preconditions
The practical impact depends on the deployment.
The deployment uses a filesystem-backed WsgiDAV share.
The attacker can send WebDAV requests accepted by that share. This may be an anonymous share or an authenticated WebDAV user. This is not an authentication bypass.
Details
The issue is in FilesystemProvider._loc_to_file_path(). The method builds a candidate path with os.path.abspath(os.path.join(root_path, *path_parts)), then checks containment with file_path.startswith(root_path). This is not path-boundary aware. For example, if the configured share root is /tmp/share, a resolved sibling path such as /tmp/share_evil/secret.txt still starts with the string /tmp/share.
In a local proof, this allowed GET, PUT, and DELETE requests to operate on files outside the configured share root.
The WSGI/server layer forwards the encoded dot segment to WsgiDAV's PATH_INFO. The local proof used /%2e%2e/..., which wsgiref passed through as /../....
A sibling or neighboring path exists whose absolute path starts with the configured root path string, such as /tmp/share and /tmp/share_evil.
The WsgiDAV process has OS permissions for the outside path.
{
"affected": [
{
"database_specific": {
"last_known_affected_version_range": "\u003c= 4.3.3"
},
"package": {
"ecosystem": "PyPI",
"name": "wsgidav"
},
"ranges": [
{
"events": [
{
"introduced": "0"
},
{
"fixed": "4.3.4"
}
],
"type": "ECOSYSTEM"
}
]
}
],
"aliases": [
"CVE-2026-48099"
],
"database_specific": {
"cwe_ids": [
"CWE-22"
],
"github_reviewed": true,
"github_reviewed_at": "2026-06-11T20:28:45Z",
"nvd_published_at": null,
"severity": "HIGH"
},
"details": "### Impact\nWsgiDAV 4.3.3 can allow a WebDAV request path containing an encoded parent-directory segment to escape the configured filesystem share root in a specific path layout.\n\n### Patches\nThe issue is fixed with version 4.3.4.\n\n### Preconditions\n\nThe practical impact depends on the deployment.\n\nThe deployment uses a filesystem-backed WsgiDAV share.\n\nThe attacker can send WebDAV requests accepted by that share. This may be an anonymous share or an authenticated WebDAV user. This is not an authentication bypass.\n\n### Details\n\nThe issue is in `FilesystemProvider._loc_to_file_path()`. The method builds a candidate path with `os.path.abspath(os.path.join(root_path, *path_parts))`, then checks containment with `file_path.startswith(root_path)`. This is not path-boundary aware. For example, if the configured share root is `/tmp/share`, a resolved sibling path such as `/tmp/share_evil/secret.txt` still starts with the string `/tmp/share`.\n\nIn a local proof, this allowed GET, PUT, and DELETE requests to operate on files outside the configured share root.\n\nThe WSGI/server layer forwards the encoded dot segment to WsgiDAV\u0027s PATH_INFO. The local proof used `/%2e%2e/...`, which wsgiref passed through as `/../...`.\n\nA sibling or neighboring path exists whose absolute path starts with the configured root path string, such as `/tmp/share` and `/tmp/share_evil`.\n\nThe WsgiDAV process has OS permissions for the outside path.",
"id": "GHSA-wxq4-cc2q-338q",
"modified": "2026-06-11T20:28:45Z",
"published": "2026-06-11T20:28:45Z",
"references": [
{
"type": "WEB",
"url": "https://github.com/mar10/wsgidav/security/advisories/GHSA-wxq4-cc2q-338q"
},
{
"type": "WEB",
"url": "https://github.com/mar10/wsgidav/commit/f894ed8656d7bdd7438ab8148c5a02546cb15183"
},
{
"type": "PACKAGE",
"url": "https://github.com/mar10/wsgidav"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:L",
"type": "CVSS_V3"
}
],
"summary": "WsgiDAV encoded dot segments can escape filesystem share roots"
}
GHSA-WXW5-WRPR-5MPW
Vulnerability from github – Published: 2022-05-17 04:21 – Updated: 2022-05-17 04:21Absolute path traversal vulnerability in the untar_block function in win32/untar.c in Pidgin before 2.10.10 on Windows allows remote attackers to write to arbitrary files via a drive name in a tar archive of a smiley theme.
{
"affected": [],
"aliases": [
"CVE-2014-3697"
],
"database_specific": {
"cwe_ids": [
"CWE-22"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2014-10-29T10:55:00Z",
"severity": "MODERATE"
},
"details": "Absolute path traversal vulnerability in the untar_block function in win32/untar.c in Pidgin before 2.10.10 on Windows allows remote attackers to write to arbitrary files via a drive name in a tar archive of a smiley theme.",
"id": "GHSA-wxw5-wrpr-5mpw",
"modified": "2022-05-17T04:21:11Z",
"published": "2022-05-17T04:21:11Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2014-3697"
},
{
"type": "WEB",
"url": "http://hg.pidgin.im/pidgin/main/rev/68b8eb10977f"
},
{
"type": "WEB",
"url": "http://lists.opensuse.org/opensuse-updates/2014-11/msg00023.html"
},
{
"type": "WEB",
"url": "http://lists.opensuse.org/opensuse-updates/2014-11/msg00037.html"
},
{
"type": "WEB",
"url": "http://pidgin.im/news/security/?id=89"
}
],
"schema_version": "1.4.0",
"severity": []
}
GHSA-X234-R5FG-X52M
Vulnerability from github – Published: 2024-06-06 21:30 – Updated: 2024-06-06 22:57In h2oai/h2o-3 version 3.40.0.4, an exposure of sensitive information vulnerability exists due to an arbitrary system path lookup feature. This vulnerability allows any remote user to view full paths in the entire file system where h2o-3 is hosted. Specifically, the issue resides in the Typeahead API call, which when requested with a typeahead lookup of '/', exposes the root filesystem including directories such as /home, /usr, /bin, among others. This vulnerability could allow attackers to explore the entire filesystem, and when combined with a Local File Inclusion (LFI) vulnerability, could make exploitation of the server trivial.
{
"affected": [
{
"package": {
"ecosystem": "PyPI",
"name": "h2o"
},
"ranges": [
{
"events": [
{
"introduced": "0"
},
{
"last_affected": "3.40.0.4"
}
],
"type": "ECOSYSTEM"
}
]
}
],
"aliases": [
"CVE-2024-5550"
],
"database_specific": {
"cwe_ids": [
"CWE-200",
"CWE-22"
],
"github_reviewed": true,
"github_reviewed_at": "2024-06-06T22:57:21Z",
"nvd_published_at": "2024-06-06T19:16:09Z",
"severity": "MODERATE"
},
"details": "In h2oai/h2o-3 version 3.40.0.4, an exposure of sensitive information vulnerability exists due to an arbitrary system path lookup feature. This vulnerability allows any remote user to view full paths in the entire file system where h2o-3 is hosted. Specifically, the issue resides in the Typeahead API call, which when requested with a typeahead lookup of \u0027/\u0027, exposes the root filesystem including directories such as /home, /usr, /bin, among others. This vulnerability could allow attackers to explore the entire filesystem, and when combined with a Local File Inclusion (LFI) vulnerability, could make exploitation of the server trivial.",
"id": "GHSA-x234-r5fg-x52m",
"modified": "2024-06-06T22:57:21Z",
"published": "2024-06-06T21:30:37Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2024-5550"
},
{
"type": "PACKAGE",
"url": "https://github.com/h2oai/h2o-3"
},
{
"type": "WEB",
"url": "https://huntr.com/bounties/e76372c2-39be-4984-a7c8-7048a75a25dc"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N",
"type": "CVSS_V3"
}
],
"summary": "Arbitrary system path lookup in h20"
}
GHSA-X23C-QWC7-6VG8
Vulnerability from github – Published: 2022-05-17 00:16 – Updated: 2022-05-17 00:16LvyeCMS through 3.1 allows remote attackers to upload and execute arbitrary PHP code via directory traversal sequences in the dir parameter, in conjunction with PHP code in the content parameter, within a template Style add request to index.php.
{
"affected": [],
"aliases": [
"CVE-2017-16903"
],
"database_specific": {
"cwe_ids": [
"CWE-22"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2017-11-20T19:29:00Z",
"severity": "CRITICAL"
},
"details": "LvyeCMS through 3.1 allows remote attackers to upload and execute arbitrary PHP code via directory traversal sequences in the dir parameter, in conjunction with PHP code in the content parameter, within a template Style add request to index.php.",
"id": "GHSA-x23c-qwc7-6vg8",
"modified": "2022-05-17T00:16:19Z",
"published": "2022-05-17T00:16:19Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2017-16903"
},
{
"type": "WEB",
"url": "https://github.com/SQYY/CVE/blob/master/Lvyecms_G.txt"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
"type": "CVSS_V3"
}
]
}
GHSA-X257-FQGC-R4PQ
Vulnerability from github – Published: 2022-05-02 06:19 – Updated: 2022-05-02 06:19Directory traversal vulnerability in news/include/customize.php in Web Server Creator - Web Portal 0.1 allows remote attackers to read arbitrary files via a .. (dot dot) in the l parameter.
{
"affected": [],
"aliases": [
"CVE-2010-1115"
],
"database_specific": {
"cwe_ids": [
"CWE-22"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2010-03-25T17:30:00Z",
"severity": "MODERATE"
},
"details": "Directory traversal vulnerability in news/include/customize.php in Web Server Creator - Web Portal 0.1 allows remote attackers to read arbitrary files via a .. (dot dot) in the l parameter.",
"id": "GHSA-x257-fqgc-r4pq",
"modified": "2022-05-02T06:19:07Z",
"published": "2022-05-02T06:19:07Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2010-1115"
},
{
"type": "WEB",
"url": "https://exchange.xforce.ibmcloud.com/vulnerabilities/55725"
},
{
"type": "WEB",
"url": "http://www.packetstormsecurity.com/1001-exploits/webservercreator-traversalxssrfi.txt"
},
{
"type": "WEB",
"url": "http://www.securityfocus.com/bid/37841"
}
],
"schema_version": "1.4.0",
"severity": []
}
GHSA-X263-68HQ-F692
Vulnerability from github – Published: 2022-04-12 00:00 – Updated: 2026-07-05 03:30A Directory Traversal vulnerability exists in KevinLAB Inc Building Energy Management System 4ST BEMS 1.0.0 via the page GET parameter in index.php.
{
"affected": [],
"aliases": [
"CVE-2021-37293"
],
"database_specific": {
"cwe_ids": [
"CWE-22"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2022-04-11T19:15:00Z",
"severity": "MODERATE"
},
"details": "A Directory Traversal vulnerability exists in KevinLAB Inc Building Energy Management System 4ST BEMS 1.0.0 via the page GET parameter in index.php.",
"id": "GHSA-x263-68hq-f692",
"modified": "2026-07-05T03:30:47Z",
"published": "2022-04-12T00:00:34Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2021-37293"
},
{
"type": "WEB",
"url": "https://www.zeroscience.mk/en/vulnerabilities"
},
{
"type": "WEB",
"url": "http://www.kevinlab.com"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N",
"type": "CVSS_V3"
}
]
}
GHSA-X26F-26QW-HHHX
Vulnerability from github – Published: 2018-07-26 15:22 – Updated: 2023-01-31 01:37Versions of hekto before 0.2.3 are vulnerable to path traversal. This allows a remote attacker to read content of arbitrary files.
Recommendation
Update to version 0.2.3 or later.
{
"affected": [
{
"package": {
"ecosystem": "npm",
"name": "hekto"
},
"ranges": [
{
"events": [
{
"introduced": "0"
},
{
"fixed": "0.2.3"
}
],
"type": "ECOSYSTEM"
}
]
}
],
"aliases": [
"CVE-2018-3725"
],
"database_specific": {
"cwe_ids": [
"CWE-22"
],
"github_reviewed": true,
"github_reviewed_at": "2020-06-16T22:01:37Z",
"nvd_published_at": "2018-06-07T02:29:00Z",
"severity": "HIGH"
},
"details": "Versions of `hekto` before 0.2.3 are vulnerable to path traversal. This allows a remote attacker to read content of arbitrary files.\n\n\n## Recommendation\n\nUpdate to version 0.2.3 or later.",
"id": "GHSA-x26f-26qw-hhhx",
"modified": "2023-01-31T01:37:40Z",
"published": "2018-07-26T15:22:00Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2018-3725"
},
{
"type": "WEB",
"url": "https://hackerone.com/reports/311218"
},
{
"type": "ADVISORY",
"url": "https://github.com/advisories/GHSA-x26f-26qw-hhhx"
},
{
"type": "WEB",
"url": "https://www.npmjs.com/advisories/586"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N",
"type": "CVSS_V3"
}
],
"summary": "Path Traversal in hekto"
}
Mitigation MIT-5.1
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.
- When validating filenames, use stringent allowlists that limit the character set to be used. If feasible, only allow a single "." character in the filename to avoid weaknesses such as CWE-23, and exclude directory separators such as "/" to avoid CWE-36. Use a list of allowable file extensions, which will help to avoid CWE-434.
- Do not rely exclusively on a filtering mechanism that removes potentially dangerous characters. This is equivalent to a denylist, which may be incomplete (CWE-184). For example, filtering "/" is insufficient protection if the filesystem also supports the use of "\" as a directory separator. Another possible error could occur when the filtering is applied in a way that still produces dangerous data (CWE-182). For example, if "../" sequences are removed from the ".../...//" string in a sequential fashion, two instances of "../" would be removed from the original string, but the remaining characters would still form the "../" string.
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 MIT-20.1
Strategy: Input Validation
- Inputs should be decoded and canonicalized to the application's current internal representation before being validated (CWE-180). Make sure that the application does not decode the same input twice (CWE-174). Such errors could be used to bypass allowlist validation schemes by introducing dangerous inputs after they have been checked.
- Use a built-in path canonicalization function (such as realpath() in C) that produces the canonical version of the pathname, which effectively removes ".." sequences and symbolic links (CWE-23, CWE-59). This includes:
- realpath() in C
- getCanonicalPath() in Java
- GetFullPath() in ASP.NET
- realpath() or abs_path() in Perl
- realpath() in PHP
Mitigation MIT-4
Strategy: Libraries or Frameworks
Use a vetted library or framework that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid [REF-1482].
Mitigation MIT-29
Strategy: Firewall
Use an application firewall that can detect attacks against this weakness. It can be beneficial in cases in which the code cannot be fixed (because it is controlled by a third party), as an emergency prevention measure while more comprehensive software assurance measures are applied, or to provide defense in depth [REF-1481].
Mitigation MIT-17
Strategy: Environment Hardening
Run your code using the lowest privileges that are required to accomplish the necessary tasks [REF-76]. If possible, create isolated accounts with limited privileges that are only used for a single task. That way, a successful attack will not immediately give the attacker access to the rest of the software or its environment. For example, database applications rarely need to run as the database administrator, especially in day-to-day operations.
Mitigation MIT-21.1
Strategy: Enforcement by Conversion
- When the set of acceptable objects, such as filenames or URLs, is limited or known, create a mapping from a set of fixed input values (such as numeric IDs) to the actual filenames or URLs, and reject all other inputs.
- For example, ID 1 could map to "inbox.txt" and ID 2 could map to "profile.txt". Features such as the ESAPI AccessReferenceMap [REF-185] provide this capability.
Mitigation MIT-22
Strategy: Sandbox or Jail
- Run the code in a "jail" or similar sandbox environment that enforces strict boundaries between the process and the operating system. This may effectively restrict which files can be accessed in a particular directory or which commands can be executed by the software.
- OS-level examples include the Unix chroot jail, AppArmor, and SELinux. In general, managed code may provide some protection. For example, java.io.FilePermission in the Java SecurityManager allows the software to specify restrictions on file operations.
- This may not be a feasible solution, and it only limits the impact to the operating system; the rest of the application may still be subject to compromise.
- Be careful to avoid CWE-243 and other weaknesses related to jails.
Mitigation MIT-34
Strategy: Attack Surface Reduction
- Store library, include, and utility files outside of the web document root, if possible. Otherwise, store them in a separate directory and use the web server's access control capabilities to prevent attackers from directly requesting them. One common practice is to define a fixed constant in each calling program, then check for the existence of the constant in the library/include file; if the constant does not exist, then the file was directly requested, and it can exit immediately.
- This significantly reduces the chance of an attacker being able to bypass any protection mechanisms that are in the base program but not in the include files. It will also reduce the attack surface.
Mitigation MIT-39
- Ensure that error messages only contain minimal details that are useful to the intended audience and no one else. The messages need to strike the balance between being too cryptic (which can confuse users) or being too detailed (which may reveal more than intended). The messages should not reveal the methods that were used to determine the error. Attackers can use detailed information to refine or optimize their original attack, thereby increasing their chances of success.
- If errors must be captured in some detail, record them in log messages, but consider what could occur if the log messages can be viewed by attackers. Highly sensitive information such as passwords should never be saved to log files.
- Avoid inconsistent messaging that might accidentally tip off an attacker about internal state, such as whether a user account exists or not.
- In the context of path traversal, error messages which disclose path information can help attackers craft the appropriate attack strings to move through the file system hierarchy.
Mitigation MIT-16
Strategy: Environment Hardening
When using PHP, configure the application so that it does not use register_globals. During implementation, develop the application so that it does not rely on this feature, but be wary of implementing a register_globals emulation that is subject to weaknesses such as CWE-95, CWE-621, and similar issues.
CAPEC-126: Path Traversal
An adversary uses path manipulation methods to exploit insufficient input validation of a target to obtain access to data that should be not be retrievable by ordinary well-formed requests. A typical variety of this attack involves specifying a path to a desired file together with dot-dot-slash characters, resulting in the file access API or function traversing out of the intended directory structure and into the root file system. By replacing or modifying the expected path information the access function or API retrieves the file desired by the attacker. These attacks either involve the attacker providing a complete path to a targeted file or using control characters (e.g. path separators (/ or \) and/or dots (.)) to reach desired directories or files.
CAPEC-64: Using Slashes and URL Encoding Combined to Bypass Validation Logic
This attack targets the encoding of the URL combined with the encoding of the slash characters. An attacker can take advantage of the multiple ways of encoding a URL and abuse the interpretation of the URL. A URL may contain special character that need special syntax handling in order to be interpreted. Special characters are represented using a percentage character followed by two digits representing the octet code of the original character (%HEX-CODE). For instance US-ASCII space character would be represented with %20. This is often referred as escaped ending or percent-encoding. Since the server decodes the URL from the requests, it may restrict the access to some URL paths by validating and filtering out the URL requests it received. An attacker will try to craft an URL with a sequence of special characters which once interpreted by the server will be equivalent to a forbidden URL. It can be difficult to protect against this attack since the URL can contain other format of encoding such as UTF-8 encoding, Unicode-encoding, etc.
CAPEC-76: Manipulating Web Input to File System Calls
An attacker manipulates inputs to the target software which the target software passes to file system calls in the OS. The goal is to gain access to, and perhaps modify, areas of the file system that the target software did not intend to be accessible.
CAPEC-78: Using Escaped Slashes in Alternate Encoding
This attack targets the use of the backslash in alternate encoding. An adversary can provide a backslash as a leading character and causes a parser to believe that the next character is special. This is called an escape. By using that trick, the adversary tries to exploit alternate ways to encode the same character which leads to filter problems and opens avenues to attack.
CAPEC-79: Using Slashes in Alternate Encoding
This attack targets the encoding of the Slash characters. An adversary would try to exploit common filtering problems related to the use of the slashes characters to gain access to resources on the target host. Directory-driven systems, such as file systems and databases, typically use the slash character to indicate traversal between directories or other container components. For murky historical reasons, PCs (and, as a result, Microsoft OSs) choose to use a backslash, whereas the UNIX world typically makes use of the forward slash. The schizophrenic result is that many MS-based systems are required to understand both forms of the slash. This gives the adversary many opportunities to discover and abuse a number of common filtering problems. The goal of this pattern is to discover server software that only applies filters to one version, but not the other.