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CVE-2026-23331

udp: Unhash auto-bound connected sk from 4-tuple hash table when disconnected.

Description

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().

Timeline

  1. ID reserved

    By Linux

  2. · 2 months later

    Published

  3. · 47 days later

    Record updated

Changes after publication (a new score, a public exploit, EPSS crossing 1, 10 or 50 %, leaving KEV) are kept since November 2026; earlier ones are not known.

Scores

CVSS scores of CVE-2026-23331, by who scored it
Scored byCVSSScoreVector
NVDNVD · Analyzed3.1Medium5.5CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
EPSS (exploitation in 30 days)
0.13% · top 98% of all CVEs (10 Nov 2026)
Loading the EPSS history…

The list uses the assigner's score when there is one, then CISA's, then NVD's: Medium 5.5.

Affected products

  • Linux · Linux

    • affected 78c91ae2c6deb5d236a5a93ff2995cdd05514380 – < b955350778b8715e1b7885179979b3a68221c0fb
    • affected 78c91ae2c6deb5d236a5a93ff2995cdd05514380 – < 3b8f104880c104151f8c30f2f89df81fb59a286c
    • affected 78c91ae2c6deb5d236a5a93ff2995cdd05514380 – < 6996a2d2d0a64808c19c98002aeb5d9d1b2df6a4
  • Linux · Linux

    • affected 6.13
    • unaffected < 6.13
    • unaffected 6.18.17 – ≤ 6.18.*
    • unaffected 6.19.7 – ≤ 6.19.*
    • unaffected 7.0 – ≤ *

References

3

Sources

The same CVE in the primary databases and aggregators, to check against.

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Record last updated .