{
  "affected": [
    {
      "ranges": [
        {
          "events": [
            {
              "introduced": "4cb47a8644cc9eb8ec81190a50e79e6530d0297f"
            },
            {
              "fixed": "95b6d772bfe788331d9742d73eaa12e113b2adc4"
            },
            {
              "fixed": "7254aef4d1a7e18e887af9010e2f2dc34806789b"
            },
            {
              "fixed": "bf8b3f34c37c162357138e7c0942723b8b94fed1"
            },
            {
              "fixed": "76cd9398a0470257ab765bdf5f358a2af2e17934"
            },
            {
              "fixed": "50750d86a2e5266aba0c295483b3397843198b11"
            },
            {
              "fixed": "6dff77899b9e9fe5d854abda3a98ad04e7229ef7"
            },
            {
              "fixed": "f3f204541f280a6ecb04503a0d6794d93990ca43"
            },
            {
              "fixed": "b4bc94353050b1fa7b702bd4c6600710dd926cff"
            }
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "type": "GIT"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "Linux",
        "name": "Kernel"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "5.9.0"
            },
            {
              "fixed": "5.10.259"
            }
          ],
          "type": "ECOSYSTEM"
        },
        {
          "events": [
            {
              "introduced": "5.11.0"
            },
            {
              "fixed": "5.15.210"
            }
          ],
          "type": "ECOSYSTEM"
        },
        {
          "events": [
            {
              "introduced": "5.16.0"
            },
            {
              "fixed": "6.1.176"
            }
          ],
          "type": "ECOSYSTEM"
        },
        {
          "events": [
            {
              "introduced": "6.2.0"
            },
            {
              "fixed": "6.6.143"
            }
          ],
          "type": "ECOSYSTEM"
        },
        {
          "events": [
            {
              "introduced": "6.7.0"
            },
            {
              "fixed": "6.12.93"
            }
          ],
          "type": "ECOSYSTEM"
        },
        {
          "events": [
            {
              "introduced": "6.13.0"
            },
            {
              "fixed": "6.18.35"
            }
          ],
          "type": "ECOSYSTEM"
        },
        {
          "events": [
            {
              "introduced": "6.19.0"
            },
            {
              "fixed": "7.0.12"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "database_specific": {
    "cna_assigner": "Linux",
    "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/63xxx/CVE-2026-63994.json"
  },
  "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": "CVE-2026-63994",
  "modified": "2026-07-22T05:30:07.588610205Z",
  "published": "2026-07-19T14:56:13.896Z",
  "references": [
    {
      "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"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/63xxx/CVE-2026-63994.json"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-63994"
    },
    {
      "type": "PACKAGE",
      "url": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"
    }
  ],
  "schema_version": "1.8.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
      "type": "CVSS_V3"
    }
  ],
  "summary": "tunnels: load network headers after skb_cow() in iptunnel_pmtud_build_icmp[v6]()"
}