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tunnels: load network headers after skb_cow() in iptunnel_pmtud_build_icmp[v6]()

Type: advisorySource: Official CVE List1 source record

In the Linux kernel, the following vulnerability has been resolved: tunnels: load network headers after skb_cow() in iptunnel_pmtud_build_icmp[v6]() 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.

Announced Group revision 1
Original source ↗

CVE-2026-63994

Primary source · Revision 1

Imported from structured advisory data. Source references identify upstream records or fields; verify affected versions and your deployed configuration.

Security context

Source reference: cve:CVE-2026-63994

Linux

Source reference: /containers/cna/affected/0/product

Affected versions
Not stated in this record
Fixed versions
Not stated in this record
Prerequisites
Not stated in this record

Linux

Source reference: /containers/cna/affected/1/product

Affected versions
Not stated in this record
Fixed versions
Not stated in this record
Prerequisites
Not stated in this record

Structured affected-version data

Original package identities and version rules from this source.

[
  {
    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
    "vendor": "Linux",
    "product": "Linux",
    "versions": [
      {
        "status": "affected",
        "version": "4cb47a8644cc9eb8ec81190a50e79e6530d0297f",
        "lessThan": "95b6d772bfe788331d9742d73eaa12e113b2adc4",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "4cb47a8644cc9eb8ec81190a50e79e6530d0297f",
        "lessThan": "7254aef4d1a7e18e887af9010e2f2dc34806789b",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "4cb47a8644cc9eb8ec81190a50e79e6530d0297f",
        "lessThan": "bf8b3f34c37c162357138e7c0942723b8b94fed1",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "4cb47a8644cc9eb8ec81190a50e79e6530d0297f",
        "lessThan": "76cd9398a0470257ab765bdf5f358a2af2e17934",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "4cb47a8644cc9eb8ec81190a50e79e6530d0297f",
        "lessThan": "50750d86a2e5266aba0c295483b3397843198b11",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "4cb47a8644cc9eb8ec81190a50e79e6530d0297f",
        "lessThan": "6dff77899b9e9fe5d854abda3a98ad04e7229ef7",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "4cb47a8644cc9eb8ec81190a50e79e6530d0297f",
        "lessThan": "f3f204541f280a6ecb04503a0d6794d93990ca43",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "4cb47a8644cc9eb8ec81190a50e79e6530d0297f",
        "lessThan": "b4bc94353050b1fa7b702bd4c6600710dd926cff",
        "versionType": "git"
      }
    ],
    "programFiles": [
      "net/ipv4/ip_tunnel_core.c"
    ],
    "defaultStatus": "unaffected"
  },
  {
    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
    "vendor": "Linux",
    "product": "Linux",
    "versions": [
      {
        "status": "affected",
        "version": "5.9"
      },
      {
        "status": "unaffected",
        "version": "0",
        "lessThan": "5.9",
        "versionType": "semver"
      },
      {
        "status": "unaffected",
        "version": "5.10.259",
        "versionType": "semver",
        "lessThanOrEqual": "5.10.*"
      },
      {
        "status": "unaffected",
        "version": "5.15.210",
        "versionType": "semver",
        "lessThanOrEqual": "5.15.*"
      },
      {
        "status": "unaffected",
        "version": "6.1.176",
        "versionType": "semver",
        "lessThanOrEqual": "6.1.*"
      },
      {
        "status": "unaffected",
        "version": "6.6.143",
        "versionType": "semver",
        "lessThanOrEqual": "6.6.*"
      },
      {
        "status": "unaffected",
        "version": "6.12.93",
        "versionType": "semver",
        "lessThanOrEqual": "6.12.*"
      },
      {
        "status": "unaffected",
        "version": "6.18.35",
        "versionType": "semver",
        "lessThanOrEqual": "6.18.*"
      },
      {
        "status": "unaffected",
        "version": "7.0.12",
        "versionType": "semver",
        "lessThanOrEqual": "7.0.*"
      },
      {
        "status": "unaffected",
        "version": "7.1",
        "versionType": "original_commit_for_fix",
        "lessThanOrEqual": "*"
      }
    ],
    "programFiles": [
      "net/ipv4/ip_tunnel_core.c"
    ],
    "defaultStatus": "affected"
  }
]
Related CVEs
CVE-2026-63994

Source reference: /cveMetadata/cveId

Publisher severity

critical

Source reference: /containers/cna/metrics

Event
#40923 · Revision 1
Added to Heist Feed
Publisher date
Read the original announcement

Revision history

  1. CVE-2026-63994 · Revision 1Source updated