CVE-2026-23331

Denial of service via stale UDP hash entries

Published Mar 25, 2026 · Updated Mar 25, 2026

Denial of service in affected Linux kernel releases beginning with 6.13 allows local users to interrupt the system through UDP socket operations. On disconnect, __udp_disconnect() rehashes a wildcard-bound socket into another 4-tuple slot instead of removing it, leaving unreachable chain garbage and stale port-address accounting. A local low-privileged user must create and manipulate the sockets; published evidence establishes availability impact without specifying a crash, hang, or other failure mode.

CVSS severity5.5
Medium
EPSS probability0.12%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
Coverage for this vulnerability

See if you're affected

Explore vulnerability checks for your environment with Hinoki.

Book a demo

Summary

What happened

Denial of service in affected Linux kernel releases beginning with 6.13 allows local users to interrupt the system through UDP socket operations. On disconnect, __udp_disconnect() rehashes a wildcard-bound socket into another 4-tuple slot instead of removing it, leaving unreachable chain garbage and stale port-address accounting. A local low-privileged user must create and manipulate the sockets; published evidence establishes availability impact without specifying a crash, hang, or other failure mode.

The record

CVE
CVE-2026-23331
Published
Mar 25, 2026
Updated
Mar 25, 2026
Vendor
The Linux Kernel Organization
Product
Linux Kernel
Classifications
T1499.004
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Mar 25, 2026CVE publishedPublication date reported by the CVE source.
  2. Mar 25, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=6.13
  2. Affected versionversion=78c91ae2c6deb5d236a5a93ff2995cdd05514380 <3b8f104880c104151f8c30f2f89df81fb59a286c
  3. Affected versionversion=78c91ae2c6deb5d236a5a93ff2995cdd05514380 <6996a2d2d0a64808c19c98002aeb5d9d1b2df6a4
  4. Affected versionversion=78c91ae2c6deb5d236a5a93ff2995cdd05514380 <b955350778b8715e1b7885179979b3a68221c0fb

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linux Kernelversion=6.13; version=78c91ae2c6deb5d236a5a93ff2995cdd05514380 <3b8f104880c104151f8c30f2f89df81fb59a286c; version=78c91ae2c6deb5d236a5a93ff2995cdd05514380 <6996a2d2d0a64808c19c98002aeb5d9d1b2df6a4; version=78c91ae2c6deb5d236a5a93ff2995cdd05514380 <b955350778b8715e1b7885179979b3a68221c0fb

Published CVSS scores

5.5NIST NVDCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

T1499.004Application or System Exploitation

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

See the directory against your own environment.

Your stack

Check the software in your environment

Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.

Book a demo