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GHSA-4JHV-HQG8-9J35

Vulnerability from github – Published: 2026-09-04 18:31 – Updated: 2026-09-04 18:31
VLAI
Details

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

ipv6: fix use-after-free in ip6_finish_output2()

ip6_finish_output2() caches a pointer to the IPv6 destination address (daddr) before invoking lwtunnel_xmit(). The LWT-BPF transmit path or other encapsulation operations within lwtunnel_xmit() can reallocate the skb head, freeing the memory that daddr points to. When lwtunnel_xmit() returns LWTUNNEL_XMIT_CONTINUE, the function continues to use the stale daddr pointer to compute the nexthop and to look up or create the neighbour entry. This results in a use-after-free read, which can leak sensitive kernel data, pollute the neighbour table with arbitrary values, misdirect traffic, or crash the system.

Fix this by re-fetching the IPv6 header and the destination address pointer after lwtunnel_xmit() returns LWTUNNEL_XMIT_CONTINUE, ensuring that the subsequent nexthop computation and neighbour lookup operate on valid memory.

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{
  "affected": [],
  "aliases": [
    "CVE-2026-80792"
  ],
  "database_specific": {
    "cwe_ids": [],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-09-04T16:18:05Z",
    "severity": null
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nipv6: fix use-after-free in ip6_finish_output2()\n\nip6_finish_output2() caches a pointer to the IPv6 destination\naddress (daddr) before invoking lwtunnel_xmit().  The LWT-BPF\ntransmit path or other encapsulation operations within\nlwtunnel_xmit() can reallocate the skb head, freeing the memory\nthat daddr points to.  When lwtunnel_xmit() returns\nLWTUNNEL_XMIT_CONTINUE, the function continues to use the stale\ndaddr pointer to compute the nexthop and to look up or create the\nneighbour entry.  This results in a use-after-free read, which can\nleak sensitive kernel data, pollute the neighbour table with\narbitrary values, misdirect traffic, or crash the system.\n\nFix this by re-fetching the IPv6 header and the destination\naddress pointer after lwtunnel_xmit() returns\nLWTUNNEL_XMIT_CONTINUE, ensuring that the subsequent nexthop\ncomputation and neighbour lookup operate on valid memory.",
  "id": "GHSA-4jhv-hqg8-9j35",
  "modified": "2026-09-04T18:31:26Z",
  "published": "2026-09-04T18:31:26Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-80792"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/087ee0d914aaae929f1660c9ca878e367655ba1a"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/3c770ac4e6f07af7c7b40c474a3efc61ffed7862"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/3dc98e5fe82d069dd29b124ffbdb679331dfea43"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/73a187384a8c8b983c7fea046d716b6752a1e7a3"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/75e0a544ebe9af663ef53ca21e9e9185c51fb54a"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/99219c82804f266189388e8bf1cf5135d10d5515"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/c95f01b78266828a57060d754fcbfc92123a98ed"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/d0d48d999b0eee6bb176ef4e39d9be868fa80f7e"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/d960881b9312e781a3429aabceb223ce6b7c882f"
    }
  ],
  "schema_version": "1.4.0",
  "severity": []
}



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