GHSA-XF3M-WP4C-WRGW

Vulnerability from github – Published: 2026-10-18 18:31 – Updated: 2026-10-24 15:32
VLAI
Details

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

net: openvswitch: conntrack: avoid modifying shared unconfirmed ct entry

In a case where skb with an unconfirmed ct entry gets cloned, we may end up committing both but with different sets of extensions.

The series of events:

  1. The first clone wants to commit and runs the helpers wiring up the extension pointer into the expectation list.
  2. Then it looses the confirmation keeping the entry unconfirmed.
  3. Second clone now wants to commit labels and adds the new extension for that breaking the pointer in the expectation list causing UAF on the destruction path later.

While this is possible to trigger, there should be no practical network pipeline where committing both clones without modifications into the same zone is needed. So, let's just reset the entry in case for some reason we got an skb with a shared one during commit. This doesn't affect any known use cases, but avoids any potential problems with sharing and modification of the unconfirmed ct entry.

The fixes tag points to the introduction of helpers, since that's the main UAF trigger for the sharing.

Severity
7.8 (High)
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Show details on source website
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{
  "affected": [],
  "aliases": [
    "CVE-2026-98491"
  ],
  "database_specific": {
    "cwe_ids": [],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-10-18T16:17:00Z",
    "severity": "HIGH"
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet: openvswitch: conntrack: avoid modifying shared unconfirmed ct entry\n\nIn a case where skb with an unconfirmed ct entry gets cloned, we may\nend up committing both but with different sets of extensions.\n\nThe series of events:\n\n 1. The first clone wants to commit and runs the helpers wiring up\n    the extension pointer into the expectation list.\n 2. Then it looses the confirmation keeping the entry unconfirmed.\n 3. Second clone now wants to commit labels and adds the new extension\n    for that breaking the pointer in the expectation list causing\n    UAF on the destruction path later.\n\nWhile this is possible to trigger, there should be no practical\nnetwork pipeline where committing both clones without modifications\ninto the same zone is needed.  So, let\u0027s just reset the entry in case\nfor some reason we got an skb with a shared one during commit.  This\ndoesn\u0027t affect any known use cases, but avoids any potential problems\nwith sharing and modification of the unconfirmed ct entry.\n\nThe fixes tag points to the introduction of helpers, since that\u0027s the\nmain UAF trigger for the sharing.",
  "id": "GHSA-xf3m-wp4c-wrgw",
  "modified": "2026-10-24T15:32:46Z",
  "published": "2026-10-18T18:31:51Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-98491"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/26b2bd70d22457556e2fa01cbf1192cb1a94d619"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/37e3c878b183a115f9a114067f9ef3b408ad27fb"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/457e0df1b5711fbeb7ba1b6bfd826f5ef30e7e55"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/55e5256adf3940e71802e2f749cacf81518726b0"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/707c2dc77891a874f4e8c52c285a511079164ec8"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/de41ee24f77b0fc45397db3e277cae2adbd43dfe"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/e0fa5ea434b7e8467ef3adc64e3858b1ca2a642d"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/e2829ae5459ddb5fce526b2e84697edf6c0c3cef"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
      "type": "CVSS_V3"
    }
  ]
}



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