FKIE_CVE-2026-63994

Vulnerability from fkie_nvd - Published: 2026-07-19 16:17 - Updated: 2026-07-20 15:17
Severity
9.8 (Critical) - CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Summary
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.
References
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/50750d86a2e5266aba0c295483b3397843198b11
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/6dff77899b9e9fe5d854abda3a98ad04e7229ef7
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/7254aef4d1a7e18e887af9010e2f2dc34806789b
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/76cd9398a0470257ab765bdf5f358a2af2e17934
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/95b6d772bfe788331d9742d73eaa12e113b2adc4
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/b4bc94353050b1fa7b702bd4c6600710dd926cff
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/bf8b3f34c37c162357138e7c0942723b8b94fed1
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/f3f204541f280a6ecb04503a0d6794d93990ca43
Impacted products
Vendor Product Version
To clipboard 

{
  "affected": [
    {
      "affectedData": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "net/ipv4/ip_tunnel_core.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "95b6d772bfe788331d9742d73eaa12e113b2adc4",
              "status": "affected",
              "version": "4cb47a8644cc9eb8ec81190a50e79e6530d0297f",
              "versionType": "git"
            },
            {
              "lessThan": "7254aef4d1a7e18e887af9010e2f2dc34806789b",
              "status": "affected",
              "version": "4cb47a8644cc9eb8ec81190a50e79e6530d0297f",
              "versionType": "git"
            },
            {
              "lessThan": "bf8b3f34c37c162357138e7c0942723b8b94fed1",
              "status": "affected",
              "version": "4cb47a8644cc9eb8ec81190a50e79e6530d0297f",
              "versionType": "git"
            },
            {
              "lessThan": "76cd9398a0470257ab765bdf5f358a2af2e17934",
              "status": "affected",
              "version": "4cb47a8644cc9eb8ec81190a50e79e6530d0297f",
              "versionType": "git"
            },
            {
              "lessThan": "50750d86a2e5266aba0c295483b3397843198b11",
              "status": "affected",
              "version": "4cb47a8644cc9eb8ec81190a50e79e6530d0297f",
              "versionType": "git"
            },
            {
              "lessThan": "6dff77899b9e9fe5d854abda3a98ad04e7229ef7",
              "status": "affected",
              "version": "4cb47a8644cc9eb8ec81190a50e79e6530d0297f",
              "versionType": "git"
            },
            {
              "lessThan": "f3f204541f280a6ecb04503a0d6794d93990ca43",
              "status": "affected",
              "version": "4cb47a8644cc9eb8ec81190a50e79e6530d0297f",
              "versionType": "git"
            },
            {
              "lessThan": "b4bc94353050b1fa7b702bd4c6600710dd926cff",
              "status": "affected",
              "version": "4cb47a8644cc9eb8ec81190a50e79e6530d0297f",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "net/ipv4/ip_tunnel_core.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "5.9"
            },
            {
              "lessThan": "5.9",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "5.10.*",
              "status": "unaffected",
              "version": "5.10.259",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "5.15.*",
              "status": "unaffected",
              "version": "5.15.210",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.1.*",
              "status": "unaffected",
              "version": "6.1.176",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.6.*",
              "status": "unaffected",
              "version": "6.6.143",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.12.*",
              "status": "unaffected",
              "version": "6.12.93",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.35",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.0.*",
              "status": "unaffected",
              "version": "7.0.12",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.1",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    }
  ],
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "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": "CVE-2026-63994",
  "lastModified": "2026-07-20T15:17:01.007",
  "metrics": {
    "cvssMetricV31": [
      {
        "cvssData": {
          "attackComplexity": "LOW",
          "attackVector": "NETWORK",
          "availabilityImpact": "HIGH",
          "baseScore": 9.8,
          "baseSeverity": "CRITICAL",
          "confidentialityImpact": "HIGH",
          "integrityImpact": "HIGH",
          "privilegesRequired": "NONE",
          "scope": "UNCHANGED",
          "userInteraction": "NONE",
          "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
          "version": "3.1"
        },
        "exploitabilityScore": 3.9,
        "impactScore": 5.9,
        "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "type": "Secondary"
      }
    ]
  },
  "published": "2026-07-19T16:17:38.943",
  "references": [
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/50750d86a2e5266aba0c295483b3397843198b11"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/6dff77899b9e9fe5d854abda3a98ad04e7229ef7"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/7254aef4d1a7e18e887af9010e2f2dc34806789b"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/76cd9398a0470257ab765bdf5f358a2af2e17934"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/95b6d772bfe788331d9742d73eaa12e113b2adc4"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/b4bc94353050b1fa7b702bd4c6600710dd926cff"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/bf8b3f34c37c162357138e7c0942723b8b94fed1"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/f3f204541f280a6ecb04503a0d6794d93990ca43"
    }
  ],
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
  "vulnStatus": "Received"
}



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