CVE-2025-21675

Kernel crash via stale LAG definer pointers

Published Jan 31, 2025 · Updated May 11, 2026

Double-destroy in the Linux kernel mlx5 LAG port selector allows local users to crash affected kernels during bond activation. When mlx5_lag_create_definer() fails, mlx5_lag_destroy_definers() destroys entries but leaves stale pointers in the port-selection tt_map, allowing a later failure to destroy an entry again. Reachability requires mlx5 link aggregation and repeated definer-creation failures; the resulting NULL-pointer dereference stops the kernel.

CVSS severity5.5
Medium
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

Double-destroy in the Linux kernel mlx5 LAG port selector allows local users to crash affected kernels during bond activation. When mlx5_lag_create_definer() fails, mlx5_lag_destroy_definers() destroys entries but leaves stale pointers in the port-selection tt_map, allowing a later failure to destroy an entry again. Reachability requires mlx5 link aggregation and repeated definer-creation failures; the resulting NULL-pointer dereference stops the kernel.

The record

CVE
CVE-2025-21675
Published
Jan 31, 2025
Updated
May 11, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
T1499.004
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Jan 31, 2025CVE publishedPublication date reported by the CVE source.
  2. May 11, 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=5.16
  2. Affected versionversion=dc48516ec7d369c6b80bf9f14d774287b6c428aa <1f6e619ef2a4def555b14ac2aeb4304bfccad59b
  3. Affected versionversion=dc48516ec7d369c6b80bf9f14d774287b6c428aa <473bc285378f49aa27e5b3e95a6d5ed12995d654
  4. Affected versionversion=dc48516ec7d369c6b80bf9f14d774287b6c428aa <5641e82cb55b4ecbc6366a499300917d2f3e6790
  5. Affected versionversion=dc48516ec7d369c6b80bf9f14d774287b6c428aa <efc92a260e23cf9fafb0b6f6c9beb6f8df93fab4

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=5.16; version=dc48516ec7d369c6b80bf9f14d774287b6c428aa <1f6e619ef2a4def555b14ac2aeb4304bfccad59b; version=dc48516ec7d369c6b80bf9f14d774287b6c428aa <473bc285378f49aa27e5b3e95a6d5ed12995d654; version=dc48516ec7d369c6b80bf9f14d774287b6c428aa <5641e82cb55b4ecbc6366a499300917d2f3e6790; version=dc48516ec7d369c6b80bf9f14d774287b6c428aa <efc92a260e23cf9fafb0b6f6c9beb6f8df93fab4

Published CVSS scores

5.5UbuntuCVSS: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.

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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.

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Technologies

Your stack

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Your stack

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