GHSA-9CMP-WXH9-77Q4

Vulnerability from github – Published: 2026-07-19 18:31 – Updated: 2026-07-20 15:31
VLAI
Details

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

tunnels: do not assume transport header in iptunnel_pmtud_check_icmp()

In some cases, iptunnel_pmtud_check_icmp() can be called while skb transport header is not set.

This triggers an out-of-bound access, because (typeof(skb->transport_header))~0U is 65535.

Access the icmp header based on IPv4 network header, after making sure icmp->type is present in skb linear part.

Note that iptunnel_pmtud_check_icmpv6()) is fine.

Severity
9.1 (Critical)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H
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{
  "affected": [],
  "aliases": [
    "CVE-2026-63992"
  ],
  "database_specific": {
    "cwe_ids": [],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-07-19T16:17:38Z",
    "severity": "CRITICAL"
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\ntunnels: do not assume transport header in iptunnel_pmtud_check_icmp()\n\nIn some cases, iptunnel_pmtud_check_icmp() can be called while\nskb transport header is not set.\n\nThis triggers an out-of-bound access, because\n(typeof(skb-\u003etransport_header))~0U is 65535.\n\nAccess the icmp header based on IPv4 network header,\nafter making sure icmp-\u003etype is present in skb linear part.\n\nNote that iptunnel_pmtud_check_icmpv6()) is fine.",
  "id": "GHSA-9cmp-wxh9-77q4",
  "modified": "2026-07-20T15:31:54Z",
  "published": "2026-07-19T18:31:48Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-63992"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/43368636c663cff6e59dde93cf4b8e43ac28eb93"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/509323077ef79a26ba0c60bb556e45c12c398b2d"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/5a92cb45e34749865d03daf8d3500f77b5f6644c"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/7f4f7efe7f30edd29c4988de01728bf2398217e4"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/a096b6e34f602950af9a2b0856cd93a5f4c276d7"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/c7b7ec3e69e673c0d6b57f74d21da50c485c598e"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/cb549df9ce4ee15c9d5b19ddab12cf2128e4313c"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/e917d0c69f01af2bb4fbea2b66d560a53b3ac7ec"
    }
  ],
  "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:H",
      "type": "CVSS_V3"
    }
  ]
}



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