io_uring/net: populate CONNECT filter fields for 24-byte sockaddr_in6

{
  "id": "6ec2170688e9b97bc324909d87d672ccc6b01603d050c963332add822a3182f3",
  "url": "https://osv.dev/vulnerability/CVE-2026-99042",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "io_uring/net: populate CONNECT filter fields for 24-byte sockaddr_in6",
    "summary": "In the Linux kernel, the following vulnerability has been resolved: io_uring/net: populate CONNECT filter fields for 24-byte sockaddr_in6 io_connect_bpf_populate() fills connect.port and connect.v6_addr for AF_INET6 only when addr_len >= sizeof(struct sockaddr_in6), i.e. 28 bytes. The IPv6 connect paths accept SIN6_LEN_RFC2133 (24 bytes), which already holds sin6_port and sin6_addr. io_connect() passes addr_len to the socket layer unchanged. At addr_len 24 the filter sees family AF_INET6 with port and address zero, while the kernel connects to the real destination. A filter that denies an IPv6 port or address is bypassed. Denying connect.port == P rejects [::1]:P with -EACCES at addr_len 28 but connects at addr_len 24. Use SIN6_LEN_RFC2133 as the threshold. sin6_scope_id stays zero when absent. The threshold mismatch was found by an AI coding assistant (Claude Code) comparing this hook against the net/ipv6 length checks on my instructions; it also drafted the reproducer and this patch. I verified the bypass and the fix in a VM on 7.3-rc6 and that 7.2 has the same code.",
    "evidence": "osv:CVE-2026-99042",
    "products": [
      {
        "name": {
          "value": "Kernel",
          "evidence": "/affected/1/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "7.2.11",
            "evidence": "/affected/1/ranges"
          }
        ],
        "affected_versions": []
      }
    ],
    "severity": "high",
    "structured": {
      "id": "CVE-2026-99042",
      "aliases": [
        "CVE-2026-99042"
      ],
      "metrics": [
        {
          "type": "CVSS_V3",
          "score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:N"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
              "type": "GIT",
              "events": [
                {
                  "introduced": "899bea8248cee35d54760a5e7d61a76af8e64411"
                },
                {
                  "fixed": "596a955d2d01b7e29d9fed60ebcf7c4ba518b8e5"
                },
                {
                  "fixed": "aa5d5f8e502318e783545ba5d04bb40130b83e20"
                }
              ]
            }
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-99042.json"
          }
        },
        {
          "ranges": [
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "7.2.0"
                },
                {
                  "fixed": "7.2.11"
                }
              ]
            }
          ],
          "package": {
            "name": "Kernel",
            "ecosystem": "Linux"
          },
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-99042.json"
          }
        }
      ],
      "modified": "2026-10-28T02:30:23.173690932Z",
      "provider": "osv",
      "references": [
        "https://git.kernel.org/stable/c/596a955d2d01b7e29d9fed60ebcf7c4ba518b8e5",
        "https://git.kernel.org/stable/c/aa5d5f8e502318e783545ba5d04bb40130b83e20",
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/99xxx/CVE-2026-99042.json",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-99042",
        "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/2026/99xxx/CVE-2026-99042.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-99042",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 489728,
  "published_at": "2026-10-23T12:22:01.804+00:00"
}