CVE-2025-21846: Linux kernel · acct: perform last write from workqueue
Affects Linux kernelSource GCVE Database
Not known to be exploited · CVSS 5.5 Medium.
Data as of 10 Nov 2026, 14:48 UTC
Thin evidence
One scorer or none| CISA-ADP | CVSS 3.1 | 5.5 |
|---|
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:HExploitation evidence
Disclosed: evidence found.
CVE published 12 Mar 2025
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by 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
- git.kernel.org/stable/c/8acbf4a88c6a98c8ed00afd1a7d1abcca9b4735e (opens in a new tab)
- git.kernel.org/stable/c/b03782ae707cc45e65242c7cddd8e28f1c22cde5 (opens in a new tab)
- git.kernel.org/stable/c/5d5b936cfa4b0d5670ca7420ef165a074bc008eb (opens in a new tab)
- git.kernel.org/stable/c/5ee8da9bea70dda492d61f075658939af33d8410 (opens in a new tab)
- git.kernel.org/stable/c/5c928e14a2ccd99462f2351ead627b58075bb736 (opens in a new tab)
- git.kernel.org/stable/c/5a59ced8ffc71973d42c82484a719c8f6ac8f7f7 (opens in a new tab)
- git.kernel.org/stable/c/a8136afca090412a36429cb6c2543c714d9c0f84 (opens in a new tab)
- git.kernel.org/stable/c/56d5f3eba3f5de0efdd556de4ef381e109b973a9 (opens in a new tab)
- lists.debian.org/debian-lts-announce/2025/05/msg00045.html (opens in a new tab)
- lists.debian.org/debian-lts-announce/2025/05/msg00030.html (opens in a new tab)
- cert-portal.siemens.com/productcert/html/ssa-265688.html (opens in a new tab)
- cert-portal.siemens.com/productcert/html/ssa-019113.html (opens in a new tab)
- cert-portal.siemens.com/productcert/html/ssa-457936.html (opens in a new tab)
- cert-portal.siemens.com/productcert/html/ssa-784472.html (opens in a new tab)