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GHSA-5H3V-9FCC-4VC7

Vulnerability from github – Published: 2026-08-10 15:33 – Updated: 2026-08-14 00:31

Details

In the Linux kernel, the following vulnerability has been resolved:

tcp: initialize standalone TCP-AO response padding

tcp_v4_send_ack() and tcp_v6_send_response() construct standalone TCP responses with TCP-AO options. The option length carries the actual MAC length, but the TCP header length includes the option rounded up to a four-byte boundary.

tcp_ao_hash_hdr() writes the MAC only. Thus, when the MAC length is not four-byte aligned, the one to three bytes after the MAC are left uninitialized and may be transmitted. For the normal TCP-AO hashing mode, those bytes also have to be initialized before computing the MAC.

Initialize only the alignment padding in the TCP-AO branches, before hashing the header. Use TCPOPT_NOP, as in the normal TCP-AO output path. This avoids adding work to non-AO TCP responses while preserving a valid authenticated header.

Severity

7.5 (High)


                  
                    CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N

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{
  "affected": [],
  "aliases": [
    "CVE-2026-68119"
  ],
  "database_specific": {
    "cwe_ids": [],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-08-10T13:19:56Z",
    "severity": "HIGH"
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\ntcp: initialize standalone TCP-AO response padding\n\ntcp_v4_send_ack() and tcp_v6_send_response() construct standalone TCP\nresponses with TCP-AO options.  The option length carries the actual MAC\nlength, but the TCP header length includes the option rounded up to a\nfour-byte boundary.\n\ntcp_ao_hash_hdr() writes the MAC only.  Thus, when the MAC length is not\nfour-byte aligned, the one to three bytes after the MAC are left\nuninitialized and may be transmitted.  For the normal TCP-AO hashing\nmode, those bytes also have to be initialized before computing the MAC.\n\nInitialize only the alignment padding in the TCP-AO branches, before\nhashing the header.  Use TCPOPT_NOP, as in the normal TCP-AO output path.\nThis avoids adding work to non-AO TCP responses while preserving a valid\nauthenticated header.",
  "id": "GHSA-5h3v-9fcc-4vc7",
  "modified": "2026-08-14T00:31:51Z",
  "published": "2026-08-10T15:33:36Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-68119"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/a859b280441fb02f64ed4037f03d5c0c34a7a595"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/bbb7db8c74b0b5d17a695136f0f0806ecd0118f6"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/e1a9d3cc11829c5414a75eb39c704f461936eb24"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/fadaff3f66e124c3a62237f9c881819a8ac90309"
    }
  ],
  "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"
    }
  ]
}

CVE-2026-68119 (GCVE-0-2026-68119)

Vulnerability from cvelistv5 – Published: 2026-08-10 11:58 – Updated: 2026-08-17 04:59

Title

tcp: initialize standalone TCP-AO response padding

Summary

In the Linux kernel, the following vulnerability has been resolved: tcp: initialize standalone TCP-AO response padding tcp_v4_send_ack() and tcp_v6_send_response() construct standalone TCP responses with TCP-AO options. The option length carries the actual MAC length, but the TCP header length includes the option rounded up to a four-byte boundary. tcp_ao_hash_hdr() writes the MAC only. Thus, when the MAC length is not four-byte aligned, the one to three bytes after the MAC are left uninitialized and may be transmitted. For the normal TCP-AO hashing mode, those bytes also have to be initialized before computing the MAC. Initialize only the alignment padding in the TCP-AO branches, before hashing the header. Use TCPOPT_NOP, as in the normal TCP-AO output path. This avoids adding work to non-AO TCP responses while preserving a valid authenticated header.

Severity

7.5 (High)


                        
                          CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N

Assigner

Linux mitre root

References

4 references

URL	Tags
https://git.kernel.org/stable/c/bbb7db8c74b0b5d17…
https://git.kernel.org/stable/c/fadaff3f66e124c3a…
https://git.kernel.org/stable/c/a859b280441fb02f6…
https://git.kernel.org/stable/c/e1a9d3cc11829c541…

Impacted products

2 products

Vendor	Product	Version
Linux	Linux	Affected: decde2586b34b99684faff1eab41e5c496c27fb6 , < bbb7db8c74b0b5d17a695136f0f0806ecd0118f6 (git) Affected: decde2586b34b99684faff1eab41e5c496c27fb6 , < fadaff3f66e124c3a62237f9c881819a8ac90309 (git) Affected: decde2586b34b99684faff1eab41e5c496c27fb6 , < a859b280441fb02f64ed4037f03d5c0c34a7a595 (git) Affected: decde2586b34b99684faff1eab41e5c496c27fb6 , < e1a9d3cc11829c5414a75eb39c704f461936eb24 (git)
Linux	Linux	Affected: 6.7 Unaffected: 0 , < 6.7 (semver) Unaffected: 6.12.101 , ≤ 6.12.* (semver) Unaffected: 6.18.42 , ≤ 6.18.* (semver) Unaffected: 7.1.6 , ≤ 7.1.* (semver) Unaffected: 7.2 , ≤ * (original_commit_for_fix)

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{
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      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "net/ipv4/tcp_ipv4.c",
            "net/ipv6/tcp_ipv6.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
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              "status": "affected",
              "version": "decde2586b34b99684faff1eab41e5c496c27fb6",
              "versionType": "git"
            },
            {
              "lessThan": "fadaff3f66e124c3a62237f9c881819a8ac90309",
              "status": "affected",
              "version": "decde2586b34b99684faff1eab41e5c496c27fb6",
              "versionType": "git"
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              "versionType": "git"
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        },
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          "product": "Linux",
          "programFiles": [
            "net/ipv4/tcp_ipv4.c",
            "net/ipv6/tcp_ipv6.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "6.7"
            },
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              "lessThan": "6.7",
              "status": "unaffected",
              "version": "0",
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              "status": "unaffected",
              "version": "6.12.101",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.42",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.1.*",
              "status": "unaffected",
              "version": "7.1.6",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.2",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.12.101",
                  "versionStartIncluding": "6.7",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.18.42",
                  "versionStartIncluding": "6.7",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
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                  "versionStartIncluding": "6.7",
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                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
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              "negate": false,
              "operator": "OR"
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      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\ntcp: initialize standalone TCP-AO response padding\n\ntcp_v4_send_ack() and tcp_v6_send_response() construct standalone TCP\nresponses with TCP-AO options.  The option length carries the actual MAC\nlength, but the TCP header length includes the option rounded up to a\nfour-byte boundary.\n\ntcp_ao_hash_hdr() writes the MAC only.  Thus, when the MAC length is not\nfour-byte aligned, the one to three bytes after the MAC are left\nuninitialized and may be transmitted.  For the normal TCP-AO hashing\nmode, those bytes also have to be initialized before computing the MAC.\n\nInitialize only the alignment padding in the TCP-AO branches, before\nhashing the header.  Use TCPOPT_NOP, as in the normal TCP-AO output path.\nThis avoids adding work to non-AO TCP responses while preserving a valid\nauthenticated header."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "baseScore": 7.5,
            "baseSeverity": "HIGH",
            "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N",
            "version": "3.1"
          },
          "scenarios": [
            {
              "lang": "en",
              "value": "AV:N - Remote attackers reach tcp_v4_send_ack() and tcp_v6_send_response() by sending IPv4/IPv6 TCP segments into tcp_v4_rcv()/tcp_v6_rcv() SYN-RECV, TIME-WAIT, and reset paths that build standalone TCP-AO-signed ACK/RST replies transmitted back over the network.\nAC:L - On Internet-facing TCP-AO deployments (BGP/route-server successors to TCP-MD5), an attacker reliably elicits qualifying standalone responses by sending crafted TCP segments; no race, timing lottery, or uncontrollable memory layout is required beyond the peer using a non-4-byte-aligned MAC length.\nPR:N - The uninitialized bytes are returned to the remote packet sender in standalone TCP-AO ACK/RST replies; triggering requires only network reachability to a TCP-AO-enabled listener or an existing TCP-AO TIME-WAIT socket, with no local credentials on the victim host.\nUI:N - No end-user action is needed beyond normal exposure of a TCP-AO-protected network service; the attacker alone sends the triggering TCP segments and captures the padded replies.\nS:U - Kernel stack or skb memory is disclosed to a remote TCP peer within the same host kernel security authority; this is not a VM escape, IOMMU bypass, or other cross-boundary scope change.\nC:H - One to three uninitialized bytes in TCP-AO option alignment padding from the on-stack IPv4 response buffer or IPv6 skb head are transmitted on every qualifying standalone ACK/RST and can be harvested repeatedly to recover kernel stack or skb contents.\nI:N - The bug only fails to initialize alignment padding before transmission; it does not write to or corrupt kernel, socket, or application memory.\nA:N - Standalone TCP-AO responses are still transmitted successfully with no kernel oops, panic, hang, or denial of service; only confidentiality of the leaked padding bytes is affected."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-08-17T04:59:09.650Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
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        },
        {
          "url": "https://git.kernel.org/stable/c/fadaff3f66e124c3a62237f9c881819a8ac90309"
        },
        {
          "url": "https://git.kernel.org/stable/c/a859b280441fb02f64ed4037f03d5c0c34a7a595"
        },
        {
          "url": "https://git.kernel.org/stable/c/e1a9d3cc11829c5414a75eb39c704f461936eb24"
        }
      ],
      "title": "tcp: initialize standalone TCP-AO response padding",
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        "engine": "bippy-1.2.0"
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    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-68119",
    "datePublished": "2026-08-10T11:58:39.026Z",
    "dateReserved": "2026-07-30T09:28:09.369Z",
    "dateUpdated": "2026-08-17T04:59:09.650Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}

Sightings

Author	Source	Type	Date	Other

Nomenclature

Seen: The vulnerability was mentioned, discussed, or observed by the user.
Confirmed: The vulnerability has been validated from an analyst's perspective.
Published Proof of Concept: A public proof of concept is available for this vulnerability.
Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
Not confirmed: The user expressed doubt about the validity of the vulnerability.
Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

Detection rules are retrieved from Rulezet.

The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base model, served locally by ML-Gateway. They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.

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GHSA-5H3V-9FCC-4VC7

CVE-2026-68119 (GCVE-0-2026-68119)

Tags

Sightings

Nomenclature