ipv6: ioam: fix type confusion of dst_entry

{
  "id": "69f460ee1900ff7c42c745e0285125e4b82261efdd493fd6f5728cd153e363db",
  "url": "https://osv.dev/vulnerability/CVE-2026-72429",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "ipv6: ioam: fix type confusion of dst_entry",
    "summary": "In the Linux kernel, the following vulnerability has been resolved: ipv6: ioam: fix type confusion of dst_entry IOAM uses a dummy dst_entry(null_dst) to mark that the destination should not be changed after the transformation. This dst is stored in the IOAM lwt state and may be passed to dst_cache_set_ip6(). However, the IPv6 dst cache path eventually calls rt6_get_cookie(), which treats the dst_entry as part of a struct rt6_info. Since the null_dst was embedded directly as a struct dst_entry in struct ioam6_lwt, this resulted in an invalid cast and rt6_get_cookie() reading fields from the wrong object. In practice, the wrong cookie is not used while dst->obsolete is zero, but rt6_get_cookie() may also access per-cpu value when rt->sernum is zero. In this case, rt->sernum aliases ioam6_lwt::cache::reset_ts, which can become zero, making this a potential invalid pointer access. Fix this by embedding a full struct rt6_info for the dummy IPv6 route and passing its dst member to the dst APIs.",
    "evidence": "osv:CVE-2026-72429",
    "products": [
      {
        "name": {
          "value": "Kernel",
          "evidence": "/affected/1/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "6.18.40",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "7.1.5",
            "evidence": "/affected/1/ranges"
          }
        ],
        "affected_versions": []
      }
    ],
    "severity": "critical",
    "structured": {
      "id": "CVE-2026-72429",
      "aliases": [
        "CVE-2026-72429"
      ],
      "metrics": [
        {
          "type": "CVSS_V3",
          "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
              "type": "GIT",
              "events": [
                {
                  "introduced": "47ce7c854563fe8450e9cb8dcd62c6470e28076b"
                },
                {
                  "fixed": "ea24f911ead85ba3d570a31e37c52b6c949f6928"
                },
                {
                  "fixed": "5a3b2ee1e96d0580a8ed8deda6dfa430604f9ab0"
                },
                {
                  "fixed": "9ed19e11d2146076d117d51a940643990118449b"
                }
              ]
            }
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-72429.json"
          }
        },
        {
          "ranges": [
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "6.16.0"
                },
                {
                  "fixed": "6.18.40"
                }
              ]
            },
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "6.19.0"
                },
                {
                  "fixed": "7.1.5"
                }
              ]
            }
          ],
          "package": {
            "name": "Kernel",
            "ecosystem": "Linux"
          },
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-72429.json"
          }
        }
      ],
      "modified": "2026-10-28T02:30:24.917584744Z",
      "provider": "osv",
      "references": [
        "https://git.kernel.org/stable/c/5a3b2ee1e96d0580a8ed8deda6dfa430604f9ab0",
        "https://git.kernel.org/stable/c/9ed19e11d2146076d117d51a940643990118449b",
        "https://git.kernel.org/stable/c/ea24f911ead85ba3d570a31e37c52b6c949f6928",
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/72xxx/CVE-2026-72429.json",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-72429",
        "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/2026/72xxx/CVE-2026-72429.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-72429",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 491618,
  "published_at": "2026-08-15T05:56:45.53+00:00"
}