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CVE-2025-21846

5.5 · MEDIUM

In the Linux kernel, the following vulnerability has been resolved: acct: perform last write from workqueue In [1] it was reported that the acct(2) system call can be used to trigger NULL deref i…

Published Mar 12, 2025CWE-476EPSS 0.25%

Overview

CVE-2025-21846 is a medium-severity vulnerability. It was published on March 12, 2025 and has a CVSS 3.1 base score of 5.5 (MEDIUM).

This vulnerability has a CVSS 3.1 base score of 5.5, rated MEDIUM. It requires local or adjacent network access to exploit. Some level of privileges is required for exploitation.

Technical description

In the Linux kernel, the following vulnerability has been resolved:

acct: perform last write from workqueue

In [1] it was reported that the acct(2) system call can be used to

trigger NULL deref in cases where it is set to write to a file that

triggers an internal lookup. This can e.g., happen when pointing acc(2)

to /sys/power/resume. At the point the where the write to this file

happens the calling task has already exited and called exit_fs(). A

lookup will thus trigger a NULL-deref when accessing current->fs.

Reorganize the code so that the the final write happens from the

workqueue but with the caller's credentials. This preserves the

(strange) permission model and has almost no regression risk.

This api should stop to exist though.

Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

References

Refgit.kernel.org/stable/c/56d5f3eba3f5de0efdd556de4ef381e109b973a9Refgit.kernel.org/stable/c/5a59ced8ffc71973d42c82484a719c8f6ac8f7f7Refgit.kernel.org/stable/c/5c928e14a2ccd99462f2351ead627b58075bb736Refgit.kernel.org/stable/c/5d5b936cfa4b0d5670ca7420ef165a074bc008ebRefgit.kernel.org/stable/c/5ee8da9bea70dda492d61f075658939af33d8410Refgit.kernel.org/stable/c/8acbf4a88c6a98c8ed00afd1a7d1abcca9b4735eRefgit.kernel.org/stable/c/a8136afca090412a36429cb6c2543c714d9c0f84Refgit.kernel.org/stable/c/b03782ae707cc45e65242c7cddd8e28f1c22cde5Reflists.debian.org/debian-lts-announce/2025/05/msg00030.htmlReflists.debian.org/debian-lts-announce/2025/05/msg00045.html

How CyberStrike helps

Frequently asked questions

What is CVE-2025-21846?

CVE-2025-21846 is a medium-severity vulnerability. It was published on March 12, 2025 and has a CVSS 3.1 base score of 5.5 (MEDIUM).

How severe is CVE-2025-21846?

This vulnerability has a CVSS 3.1 base score of 5.5, rated MEDIUM. It requires local or adjacent network access to exploit. Some level of privileges is required for exploitation.

How do I fix or remediate CVE-2025-21846?

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

How can CyberStrike help with CVE-2025-21846?

CyberStrike is an open-source, AI-augmented pentesting engine. Rather than flag a version number, it tests whether an issue like CVE-2025-21846 is actually reachable in your own applications and APIs, then verifies each finding before reporting it. That tells you if the weakness is a real, exploitable risk in your environment or a false positive you can safely deprioritize.

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