{
  "affected": [
    {
      "ranges": [
        {
          "events": [
            {
              "introduced": "78c91ae2c6deb5d236a5a93ff2995cdd05514380"
            },
            {
              "fixed": "c21daf37d5ce9a4e234b7c42238ac1e6041e28e4"
            },
            {
              "fixed": "d1b5fd969cc53f29d02b82b05a45135de4a6087a"
            },
            {
              "fixed": "9e95b1a94c9c49b4ba722251bbca2759b9c51737"
            }
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "type": "GIT"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "Linux",
        "name": "Kernel"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "6.13.0"
            },
            {
              "fixed": "6.18.55"
            }
          ],
          "type": "ECOSYSTEM"
        },
        {
          "events": [
            {
              "introduced": "6.19.0"
            },
            {
              "fixed": "7.2.9"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "database_specific": {
    "cna_assigner": "Linux",
    "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/98xxx/CVE-2026-98595.json"
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nudp: remove a disconnected socket from the 4-tuple hash table\n\nA UDP socket bound to a specific address and port keeps its entry in the\n4-tuple hash table after it is disconnected:\n\n    sk binds to 127.0.0.1:21001\n    sk connects to 127.0.0.2:20001\t// filed in the 4-tuple table\n    sk disconnects, connect(AF_UNSPEC)\t// still filed, peer now 0.0.0.0:0\n\n__udp_disconnect() takes a socket out of that table only as a side effect\nof -\u003erehash() or -\u003eunhash(), and it skips -\u003erehash() when\nSOCK_BINDADDR_LOCK is set and -\u003eunhash() when SOCK_BINDPORT_LOCK is set.\ncommit 6996a2d2d0a6 (\"udp: Unhash auto-bound connected sk from 4-tuple hash\ntable when disconnected.\") fixed the same end state for a wildcard-bound\nsocket, by a path this one does not take.\n\nThe entry is counted whether or not anything hits it. hash4_cnt on the\nhash2 slot stays raised for as long as the socket lives, so udp_has_hash4()\nkeeps sending every packet for that address and port through the 4-tuple\nlookup first.\n\nOn IPv6 it can also be hit. __udp_disconnect() does not clear sk_v6_daddr,\nso udp_v6_rehash() files the entry under the peer the socket was connected\nto with a zero dport, and inet6_match() compares that same\nfield: a datagram from the former peer with a zero source port matches,\nand source port zero is accepted on receive. On IPv4 the peer is cleared,\nso a match would need a zero source address as well, which the routing\nlayer rejects as martian. The stale sk_v6_daddr is a separate defect, not\naddressed here; removing the entry closes this path either way.\n\nThe entry can also be relocated. __udp_disconnect() clears sk_bound_dev_if,\nso a subsequent SO_BINDTODEVICE calls -\u003erehash(), and because the receive\naddress is still specific udp_lib_rehash() moves the entry instead of\nremoving it, into the bucket that (rcv_saddr, num, 0, 0) hashes to -- a\npure function of the address and port, so every socket reaching this state\non one address and port collects in one bucket. The bucket cannot be chosen\nfrom outside, as udp_ehashfn() is seeded with a per-boot secret. This last\none became reachable only with commit 644f9108f3a5 (\"udp: Make rehash4\nindependent in udp_lib_rehash()\"), which moved the hash4 handling out of a\nbranch a disconnected socket does not take; the stale entry itself dates\nfrom the commit in Fixes.\n\nTake the socket out of the table before __udp_disconnect() runs, while it\nstill matches how it was filed. This also reaches the wildcard case ahead\nof udp_lib_rehash()'s udp_unhash4() branch, leaving that branch unreachable\nfrom udp_disconnect(); removing it belongs in net-next. udp_disconnect()\nand udp_abort() are the only UDP entries into __udp_disconnect(), which is\nshared with raw, ping and l2tp sockets that are not struct udp_sock:\nping_prot.obj_size is sizeof(struct inet_sock), so udp_hashed4() on one\nwould read past the allocation.",
  "id": "CVE-2026-98595",
  "modified": "2026-10-20T02:30:40.354593474Z",
  "published": "2026-10-18T15:19:07.840Z",
  "references": [
    {
      "type": "PACKAGE",
      "url": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/9e95b1a94c9c49b4ba722251bbca2759b9c51737"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/c21daf37d5ce9a4e234b7c42238ac1e6041e28e4"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/d1b5fd969cc53f29d02b82b05a45135de4a6087a"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/98xxx/CVE-2026-98595.json"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-98595"
    }
  ],
  "schema_version": "1.9.0",
  "summary": "udp: remove a disconnected socket from the 4-tuple hash table"
}