CVE-2025-21642

Local kernel crash via dropped namespace dereference

Published Jan 19, 2025 · Updated May 23, 2026

NULL pointer dereference in the Linux kernel 6.6.31 through 6.6.71 and 6.8.10 through 6.12.9 allows local users to crash the system. The MPTCP proc_scheduler sysctl handler reads current->nsproxy->net_ns after nsproxy has been dropped during task exit instead of using the table's net namespace. Triggering the observed Oops requires low-privileged local access and a task-exit path involving process accounting, and the reported impact is a kernel crash rather than data disclosure or modification.

CVSS severity5.5
Medium
EPSS probability0.25%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

NULL pointer dereference in the Linux kernel 6.6.31 through 6.6.71 and 6.8.10 through 6.12.9 allows local users to crash the system. The MPTCP proc_scheduler sysctl handler reads current->nsproxy->net_ns after nsproxy has been dropped during task exit instead of using the table's net namespace. Triggering the observed Oops requires low-privileged local access and a task-exit path involving process accounting, and the reported impact is a kernel crash rather than data disclosure or modification.

The record

CVE
CVE-2025-21642
Published
Jan 19, 2025
Updated
May 23, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
CWE-476, T1499
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Jan 19, 2025CVE publishedPublication date reported by the CVE source.
  2. May 23, 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=1e444f5f2a07844354ad767b44ed0a713211e26d
  2. Affected versionversion=6.6.31 <6.6.72
  3. Affected versionversion=6.8.10 <6.9
  4. Affected versionversion=6.9
  5. Affected versionversion=6963c508fd7ab66ae0b7ae3db9a62ca6267f1ae8 <6035702381c35a8f16757332381e58b348a9eaf9
  6. Affected versionversion=6963c508fd7ab66ae0b7ae3db9a62ca6267f1ae8 <d38e26e36206ae3d544d496513212ae931d1da0a
  7. Affected versionversion=daad878a509d69da1761106cb48c091dfe9d522d <c0e394fd6b887e84da17e38aaa6c1c104f9c86c2

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=1e444f5f2a07844354ad767b44ed0a713211e26d; version=6.6.31 <6.6.72; version=6.8.10 <6.9; version=6.9; version=6963c508fd7ab66ae0b7ae3db9a62ca6267f1ae8 <6035702381c35a8f16757332381e58b348a9eaf9; version=6963c508fd7ab66ae0b7ae3db9a62ca6267f1ae8 <d38e26e36206ae3d544d496513212ae931d1da0a; version=daad878a509d69da1761106cb48c091dfe9d522d <c0e394fd6b887e84da17e38aaa6c1c104f9c86c2

Published CVSS scores

5.5CISA ADP VulnrichmentCVSS: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 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-476NULL Pointer Dereference
T1499Endpoint Denial of Service

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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