GHSA-HVGQ-CH9F-27RQ

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: load network headers after skb_cow() in iptunnel_pmtud_build_icmpv6

Sashiko found that iptunnel_pmtud_build_icmp() and iptunnel_pmtud_build_icmpv6() were caching ip_hdr() and ipv6_hdr() before an skb_cow() call which can reallocate skb->head.

Fix this possible UAF by initializing the local variables after the skb_cow() call.

Remove skb_reset_network_header() calls which were not needed.

Severity
9.8 (Critical)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
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{
  "affected": [],
  "aliases": [
    "CVE-2026-63994"
  ],
  "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: load network headers after skb_cow() in iptunnel_pmtud_build_icmp[v6]()\n\nSashiko found that iptunnel_pmtud_build_icmp() and\niptunnel_pmtud_build_icmpv6() were caching ip_hdr() and ipv6_hdr()\nbefore an skb_cow() call which can reallocate skb-\u003ehead.\n\nFix this possible UAF by initializing the local variables\nafter the skb_cow() call.\n\nRemove skb_reset_network_header() calls which were not needed.",
  "id": "GHSA-hvgq-ch9f-27rq",
  "modified": "2026-07-20T15:31:54Z",
  "published": "2026-07-19T18:31:48Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-63994"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/50750d86a2e5266aba0c295483b3397843198b11"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/6dff77899b9e9fe5d854abda3a98ad04e7229ef7"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/7254aef4d1a7e18e887af9010e2f2dc34806789b"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/76cd9398a0470257ab765bdf5f358a2af2e17934"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/95b6d772bfe788331d9742d73eaa12e113b2adc4"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/b4bc94353050b1fa7b702bd4c6600710dd926cff"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/bf8b3f34c37c162357138e7c0942723b8b94fed1"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/f3f204541f280a6ecb04503a0d6794d93990ca43"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
      "type": "CVSS_V3"
    }
  ]
}



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