udp: remove a disconnected socket from the 4-tuple hash table

{
  "id": "8d83f02473966c60f7733bb606cafac5846f94308108ce1f49083e95353fa1fe",
  "url": "https://osv.dev/vulnerability/CVE-2026-98595",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "udp: remove a disconnected socket from the 4-tuple hash table",
    "summary": "In the Linux kernel, the following vulnerability has been resolved: udp: remove a disconnected socket from the 4-tuple hash table A UDP socket bound to a specific address and port keeps its entry in the 4-tuple hash table after it is disconnected: sk binds to 127.0.0.1:21001 sk connects to 127.0.0.2:20001 // filed in the 4-tuple table sk disconnects, connect(AF_UNSPEC) // still filed, peer now 0.0.0.0:0 __udp_disconnect() takes a socket out of that table only as a side effect of ->rehash() or ->unhash(), and it skips ->rehash() when SOCK_BINDADDR_LOCK is set and ->unhash() when SOCK_BINDPORT_LOCK is set. commit 6996a2d2d0a6 (\"udp: Unhash auto-bound connected sk from 4-tuple hash table when disconnected.\") fixed the same end state for a wildcard-bound socket, by a path this one does not take. The entry is counted whether or not anything hits it. hash4_cnt on the hash2 slot stays raised for as long as the socket lives, so udp_has_hash4() keeps sending every packet for that address and port through the 4-tuple lookup first. On IPv6 it can also be hit. __udp_disconnect() does not clear sk_v6_daddr, so udp_v6_rehash() files the entry under the peer the socket was connected to with a zero dport, and inet6_match() compares that same field: a datagram from the former peer with a zero source port matches, and source port zero is accepted on receive. On IPv4 the peer is cleared, so a match would need a zero source address as well, which the routing layer rejects as martian. The stale s",
    "evidence": "osv:CVE-2026-98595",
    "products": [
      {
        "name": {
          "value": "Kernel",
          "evidence": "/affected/1/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "6.18.55",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "7.2.9",
            "evidence": "/affected/1/ranges"
          }
        ],
        "affected_versions": []
      }
    ],
    "severity": "unknown",
    "structured": {
      "id": "CVE-2026-98595",
      "aliases": [
        "CVE-2026-98595"
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
              "type": "GIT",
              "events": [
                {
                  "introduced": "78c91ae2c6deb5d236a5a93ff2995cdd05514380"
                },
                {
                  "fixed": "c21daf37d5ce9a4e234b7c42238ac1e6041e28e4"
                },
                {
                  "fixed": "d1b5fd969cc53f29d02b82b05a45135de4a6087a"
                },
                {
                  "fixed": "9e95b1a94c9c49b4ba722251bbca2759b9c51737"
                }
              ]
            }
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-98595.json"
          }
        },
        {
          "ranges": [
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "6.13.0"
                },
                {
                  "fixed": "6.18.55"
                }
              ]
            },
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "6.19.0"
                },
                {
                  "fixed": "7.2.9"
                }
              ]
            }
          ],
          "package": {
            "name": "Kernel",
            "ecosystem": "Linux"
          },
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-98595.json"
          }
        }
      ],
      "modified": "2026-10-28T02:30:49.598416928Z",
      "provider": "osv",
      "references": [
        "https://git.kernel.org/stable/c/9e95b1a94c9c49b4ba722251bbca2759b9c51737",
        "https://git.kernel.org/stable/c/c21daf37d5ce9a4e234b7c42238ac1e6041e28e4",
        "https://git.kernel.org/stable/c/d1b5fd969cc53f29d02b82b05a45135de4a6087a",
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/98xxx/CVE-2026-98595.json",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-98595",
        "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/2026/98xxx/CVE-2026-98595.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-98595",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": null
  },
  "source_id": "core-osv",
  "document_id": 518076,
  "published_at": "2026-10-18T15:19:07.84+00:00"
}