CVE-2026-23331 (GCVE-0-2026-23331)

Vulnerability from cvelistv5 – Published: 2026-03-25 10:27 – Updated: 2026-05-11 22:04
VLAI
Title
udp: Unhash auto-bound connected sk from 4-tuple hash table when disconnected.
Summary
In the Linux kernel, the following vulnerability has been resolved: udp: Unhash auto-bound connected sk from 4-tuple hash table when disconnected. Let's say we bind() an UDP socket to the wildcard address with a non-zero port, connect() it to an address, and disconnect it from the address. bind() sets SOCK_BINDPORT_LOCK on sk->sk_userlocks (but not SOCK_BINDADDR_LOCK), and connect() calls udp_lib_hash4() to put the socket into the 4-tuple hash table. Then, __udp_disconnect() calls sk->sk_prot->rehash(sk). It computes a new hash based on the wildcard address and moves the socket to a new slot in the 4-tuple hash table, leaving a garbage in the chain that no packet hits. Let's remove such a socket from 4-tuple hash table when disconnected. Note that udp_sk(sk)->udp_portaddr_hash needs to be udpated after udp_hash4_dec(hslot2) in udp_unhash4().
Severity
5.5 (Medium)
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Assigner
References
Impacted products
Vendor Product Version
Linux Linux Affected: 78c91ae2c6deb5d236a5a93ff2995cdd05514380 , < b955350778b8715e1b7885179979b3a68221c0fb (git)
Affected: 78c91ae2c6deb5d236a5a93ff2995cdd05514380 , < 3b8f104880c104151f8c30f2f89df81fb59a286c (git)
Affected: 78c91ae2c6deb5d236a5a93ff2995cdd05514380 , < 6996a2d2d0a64808c19c98002aeb5d9d1b2df6a4 (git)
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Linux Linux Affected: 6.13
Unaffected: 0 , < 6.13 (semver)
Unaffected: 6.18.17 , ≤ 6.18.* (semver)
Unaffected: 6.19.7 , ≤ 6.19.* (semver)
Unaffected: 7.0 , ≤ * (original_commit_for_fix)
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{
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          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nudp: Unhash auto-bound connected sk from 4-tuple hash table when disconnected.\n\nLet\u0027s say we bind() an UDP socket to the wildcard address with a\nnon-zero port, connect() it to an address, and disconnect it from\nthe address.\n\nbind() sets SOCK_BINDPORT_LOCK on sk-\u003esk_userlocks (but not\nSOCK_BINDADDR_LOCK), and connect() calls udp_lib_hash4() to put\nthe socket into the 4-tuple hash table.\n\nThen, __udp_disconnect() calls sk-\u003esk_prot-\u003erehash(sk).\n\nIt computes a new hash based on the wildcard address and moves\nthe socket to a new slot in the 4-tuple hash table, leaving a\ngarbage in the chain that no packet hits.\n\nLet\u0027s remove such a socket from 4-tuple hash table when disconnected.\n\nNote that udp_sk(sk)-\u003eudp_portaddr_hash needs to be udpated after\nudp_hash4_dec(hslot2) in udp_unhash4()."
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    "redhat_vex": {
      "aggregate_severity": "Moderate",
      "current_release_date": "2026-06-28T07:20:19+00:00",
      "cve": "CVE-2026-23331",
      "id": "CVE-2026-23331",
      "initial_release_date": "2026-03-25T00:00:00+00:00",
      "product_status:known_affected": "14",
      "product_status:known_not_affected": "260",
      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "kernel: udp: Unhash auto-bound connected sk from 4-tuple hash table when disconnected",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-23331.json",
      "version": "3"
    }
  }
}



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Sightings

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Nomenclature

  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
  • Confirmed: The vulnerability has been validated from an analyst's perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
  • Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
  • Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
  • Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
  • Not confirmed: The user expressed doubt about the validity of the vulnerability.
  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.


Detection rules are retrieved from Rulezet.