CVE-2025-21751

Host crash via dangling mlx5 matcher

Published Feb 27, 2025 · Updated Aug 5, 2026

Use-after-free in Linux kernel mlx5 HWS matcher teardown allows local users to crash the host after a firmware command failure. When a firmware command fails during matcher disconnect, the error path reconnects the matcher, returns an error, and lets the caller free an object that remains linked in the matcher list. The path requires local low-privilege access, mlx5 hardware steering, and a firmware failure; dereferencing the dangling list entry causes an eventual kernel crash.

CVSS severity7.8
High
EPSS probability0.22%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Use-after-free in Linux kernel mlx5 HWS matcher teardown allows local users to crash the host after a firmware command failure. When a firmware command fails during matcher disconnect, the error path reconnects the matcher, returns an error, and lets the caller free an object that remains linked in the matcher list. The path requires local low-privilege access, mlx5 hardware steering, and a firmware failure; dereferencing the dangling list entry causes an eventual kernel crash.

The record

CVE
CVE-2025-21751
Published
Feb 27, 2025
Updated
Aug 5, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
CWE-416, T1499.004
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Feb 27, 2025CVE publishedPublication date reported by the CVE source.
  2. Aug 5, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

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

  1. Affected versionversion=472dd792348f6601ccaa97d5626ee4faff891901 <1ce840c7a659aa53a31ef49f0271b4fd0dc10296
  2. Affected versionversion=472dd792348f6601ccaa97d5626ee4faff891901 <23a86c76a1a197e8fbbbd0ce3e826eb58c471624
  3. Affected versionversion=472dd792348f6601ccaa97d5626ee4faff891901 <5682aad0276ff9b9b0eff3188eb6a1f504d6b436
  4. Affected versionversion=6.12

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=472dd792348f6601ccaa97d5626ee4faff891901 <1ce840c7a659aa53a31ef49f0271b4fd0dc10296; version=472dd792348f6601ccaa97d5626ee4faff891901 <23a86c76a1a197e8fbbbd0ce3e826eb58c471624; version=472dd792348f6601ccaa97d5626ee4faff891901 <5682aad0276ff9b9b0eff3188eb6a1f504d6b436; version=6.12

Published CVSS scores

7.8CISA-ADPCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/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.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-416Use After Free
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

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Your stack

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