{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "io_uring/net.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "596a955d2d01b7e29d9fed60ebcf7c4ba518b8e5",
              "status": "affected",
              "version": "899bea8248cee35d54760a5e7d61a76af8e64411",
              "versionType": "git"
            },
            {
              "lessThan": "aa5d5f8e502318e783545ba5d04bb40130b83e20",
              "status": "affected",
              "version": "899bea8248cee35d54760a5e7d61a76af8e64411",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "io_uring/net.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "7.2"
            },
            {
              "lessThan": "7.2",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.2.*",
              "status": "unaffected",
              "version": "7.2.11",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.3",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.2.11",
                  "versionStartIncluding": "7.2",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.3",
                  "versionStartIncluding": "7.2",
                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nio_uring/net: populate CONNECT filter fields for 24-byte sockaddr_in6\n\nio_connect_bpf_populate() fills connect.port and connect.v6_addr for\nAF_INET6 only when addr_len \u003e= sizeof(struct sockaddr_in6), i.e. 28\nbytes.\n\nThe IPv6 connect paths accept SIN6_LEN_RFC2133 (24 bytes), which\nalready holds sin6_port and sin6_addr. io_connect() passes addr_len to\nthe socket layer unchanged.\n\nAt addr_len 24 the filter sees family AF_INET6 with port and address\nzero, while the kernel connects to the real destination. A filter that\ndenies an IPv6 port or address is bypassed. Denying connect.port == P\nrejects [::1]:P with -EACCES at addr_len 28 but connects at addr_len 24.\n\nUse SIN6_LEN_RFC2133 as the threshold. sin6_scope_id stays zero when\nabsent.\n\nThe threshold mismatch was found by an AI coding assistant (Claude Code)\ncomparing this hook against the net/ipv6 length checks on my\ninstructions; it also drafted the reproducer and this patch. I verified\nthe bypass and the fix in a VM on 7.3-rc6 and that 7.2 has the same\ncode."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "baseScore": 8.4,
            "baseSeverity": "HIGH",
            "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:N",
            "version": "3.1"
          },
          "scenarios": [
            {
              "lang": "en",
              "value": "AV:L - An attacker reaches the patched io_connect_bpf_populate() by locally submitting IORING_OP_CONNECT through io_uring_enter(), with sqe-\u003eaddr2 supplying the malicious 24-byte length. No network packet carries the value creating the mismatch.\nAC:L - Against a CONNECT filter denying an IPv6 port or address, addr2=24 deterministically makes io_connect_bpf_populate() expose zero port/address while tcp_v6_connect() accepts and uses the real fields; no race or uncontrolled condition is involved.\nPR:L - No capability check exists in io_uring_enter(), io_connect_prep(), or io_connect(), and AF_INET6 SOCK_STREAM creation avoids inet6_create()\u0027s CAP_NET_RAW check. An ordinary confined process with access to the filtered ring can trigger the bypass.\nUI:N - The confined process prepares and submits the 24-byte sockaddr itself, and io_connect_prep() copies it during io_uring_enter(); no other user must mount, open, approve, or otherwise act.\nS:C - The false port/address view escapes the io_uring BPF CONNECT sandbox: __io_uring_run_bpf_filters() allows an operation that an inherited or ring-level filter intended to deny, reaching network resources outside that policy scope.\nC:H - After the filter sees :: and port 0, tcp_v6_connect() uses sin6_addr and sin6_port from the same 24 bytes; the confined process can establish a full socket and read responses from IPv6 services the CONNECT filter explicitly made inaccessible.\nI:H - tcp_v6_connect() stores the hidden destination in sk_v6_daddr and inet_dport and establishes the denied socket, enabling arbitrary application data and requests to be sent to IPv6 services and ports prohibited by the sandbox policy.\nA:N - The bug only substitutes zero values in the filter context; move_addr_to_kernel() safely copies 24 bytes and the IPv6 socket layer accepts that size. It introduces no corruption, out-of-bounds access, oops, hang, or resource exhaustion."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-10-24T14:10:09.161Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/596a955d2d01b7e29d9fed60ebcf7c4ba518b8e5"
        },
        {
          "url": "https://git.kernel.org/stable/c/aa5d5f8e502318e783545ba5d04bb40130b83e20"
        }
      ],
      "title": "io_uring/net: populate CONNECT filter fields for 24-byte sockaddr_in6",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-99042",
    "datePublished": "2026-10-23T12:22:01.804Z",
    "dateReserved": "2026-09-25T10:25:14.387Z",
    "dateUpdated": "2026-10-24T14:10:09.161Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}