apparmor: fix NULL pointer dereference in __unix_needs_revalidation

{
  "id": "7d3636c9e1ed9ade2840cdc7b40cc4f81f8e65b8c0523954e42c02bd36a64028",
  "url": "https://osv.dev/vulnerability/CVE-2026-45966",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "apparmor: fix NULL pointer dereference in __unix_needs_revalidation",
    "summary": "In the Linux kernel, the following vulnerability has been resolved: apparmor: fix NULL pointer dereference in __unix_needs_revalidation When receiving file descriptors via SCM_RIGHTS, both the socket pointer and the socket's sk pointer can be NULL during socket setup or teardown, causing NULL pointer dereferences in __unix_needs_revalidation(). This is a regression in AppArmor 5.0.0 (kernel 6.17+) where the new __unix_needs_revalidation() function was added without proper NULL checks. The crash manifests as: BUG: kernel NULL pointer dereference, address: 0x0000000000000018 RIP: aa_file_perm+0xb7/0x3b0 (or +0xbe/0x3b0, +0xc0/0x3e0) Call Trace: apparmor_file_receive+0x42/0x80 security_file_receive+0x2e/0x50 receive_fd+0x1d/0xf0 scm_detach_fds+0xad/0x1c0 The function dereferences sock->sk->sk_family without checking if either sock or sock->sk is NULL first. Add NULL checks for both sock and sock->sk before accessing sk_family.",
    "evidence": "osv:CVE-2026-45966",
    "products": [
      {
        "name": {
          "value": "Kernel",
          "evidence": "/affected/1/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "6.18.14",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "6.19.4",
            "evidence": "/affected/1/ranges"
          }
        ],
        "affected_versions": []
      }
    ],
    "severity": "unknown",
    "structured": {
      "id": "CVE-2026-45966",
      "aliases": [
        "CVE-2026-45966"
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
              "type": "GIT",
              "events": [
                {
                  "introduced": "88fec3526e84123997ecebd6bb6778eb4ce779b7"
                },
                {
                  "fixed": "fea017a7f6abe179decf575a2d8464c74edb3964"
                },
                {
                  "fixed": "e85bc9101afc4202aa2269967ce9d3ffbecd0994"
                },
                {
                  "fixed": "e2938ad00b21340c0362562dfedd7cfec0554d67"
                }
              ]
            }
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-45966.json"
          }
        },
        {
          "ranges": [
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "6.17.0"
                },
                {
                  "fixed": "6.18.14"
                }
              ]
            },
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "6.19.0"
                },
                {
                  "fixed": "6.19.4"
                }
              ]
            }
          ],
          "package": {
            "name": "Kernel",
            "ecosystem": "Linux"
          },
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-45966.json"
          }
        }
      ],
      "modified": "2026-10-28T02:30:26.346234289Z",
      "provider": "osv",
      "references": [
        "https://git.kernel.org/stable/c/e2938ad00b21340c0362562dfedd7cfec0554d67",
        "https://git.kernel.org/stable/c/e85bc9101afc4202aa2269967ce9d3ffbecd0994",
        "https://git.kernel.org/stable/c/fea017a7f6abe179decf575a2d8464c74edb3964",
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/45xxx/CVE-2026-45966.json",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-45966",
        "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"
      ],
      "provider_metadata": {
        "cna_assigner": "Linux",
        "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/45xxx/CVE-2026-45966.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-45966",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": null
  },
  "source_id": "core-osv",
  "document_id": 492692,
  "published_at": "2026-05-27T12:18:24.3+00:00"
}