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VulnerabilityPublished Updated

CVE-2025-21846: Linux kernel · acct: perform last write from workqueue

Affects Linux kernelSource GCVE Database

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Not known to be exploited · CVSS 5.5 Medium.

Data as of 10 Nov 2026, 14:48 UTC

CVSS 3.1 base score
5.5Medium
How severe the flaw is on the 0–10 CVSS scale.

Thin evidence

One scorer or none
CVSS scores by source
CISA-ADPCVSS 3.15.5
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 12 Mar 2025

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponized: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 10 Nov 2026.

What to do

AI-suggested

A fix has been implemented in the Linux kernel by reorganizing the acct(2) code to perform the final write from a workqueue with the caller's credentials. Users should update to the fixed Linux kernel version once available.

Description

CVE-2025-21846 is a medium severity vulnerability in the Linux kernel's acct(2) system call. It involves a NULL pointer dereference triggered when acct(2) writes to a file that causes an internal lookup, such as /sys/power/resume. The issue arises because the calling task has exited and its filesystem context is cleared, leading to a NULL dereference when accessing current->fs. The vulnerability has been addressed by reorganizing the code to perform the final write from a workqueue while preserving the caller's credentials.

References

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