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Linux KernelOperating system · Linux

CVE-2026-23331

MEDIUM · 5.5 CVSS v3.1 Published 2026-03-25
Fix available
A fix is available. Upgrade to 6.18.17 / 6.19.7 or later.
See remediation →
57/100
Remediation priority · Elevated
Zero-click Patch available

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
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().

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis

A detailed technical summary for this CVE is being prepared.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
Linux KernelOperating system
Affected:>= 6.13.1, < 6.18.17>= 6.19, < 6.19.7= 6.13= 7.0

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Local
Complexity
Low
Privileges
Low
User interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Upgrade available Upgrade to 6.18.17 / 6.19.7 or later
Fixed in 6.18.176.19.7
Vendor patch git.kernel.org →
Recommended fix High confidence

Linux Kernel 6.18.17 or later in the 6.18.y stable branch; Linux Kernel 6.19.7 or later in the 6.19.y stable branch; distributions should backport the fix to 6.13.x and 7.0 stable branches

  1. Identify your current kernel version using `uname -r`
  2. Check if your distribution provides a newer kernel package that includes the fix (6.18.17+, 6.19.7+, or the fix backported)
  3. Upgrade to the fixed kernel version using your distribution's package manager (e.g., `apt-get update && apt-get install linux-image-<version>` for Debian/Ubuntu, or `dnf update kernel` for RHEL/Fedora)
  4. Reboot the system to load the fixed kernel
  5. Verify the kernel version after reboot with `uname -r` to confirm the upgrade was successful
Caveat Upgrading kernel versions carries standard upgrade risks; ensure compatibility with custom modules and review distribution release notes for any known issues

Generated from the published advisory — verify against the referenced sources before acting.

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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2026-23331 in production — separate from our analysis above.

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What this is

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What belongs here
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  • Version or environment caveats, and links to real fixes
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