CVE-2025-21646: Linux kernel · afs: Fix the maximum cell name length
Source GCVE Database
Not known to be exploited · CVSS 5.5 Medium.
Data as of 30 Oct 2026, 01:00 UTC
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 19 Jan 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 29 Oct 2026.
What to do
AI-suggested
A fix is available in the Linux kernel that limits the maximum cell name length to 253 bytes, resolving the procfs filename length conflict. Users should apply the official kernel update containing this fix to prevent the issue. No additional mitigation steps are indicated.
Description
A vulnerability in the Linux kernel's AFS filesystem component involved improper handling of maximum cell name length. The kafs filesystem allowed cell names up to 256 bytes, but procfs limits filenames to 255 bytes, causing warnings and potential failures. The fix limits cell names to 253 bytes to ensure compatibility with procfs and DNS constraints, preventing related issues.
References
- nvd.nist.gov/vuln/detail/CVE-2025-21646 (opens in a new tab)
- git.kernel.org/stable/c/7673030efe0f8ca1056d3849d61784c6caa052af (opens in a new tab)
- git.kernel.org/stable/c/7922b1f058fe24a93730511dd0ae2e1630920096 (opens in a new tab)
- git.kernel.org/stable/c/7cb3e77e9b4e6ffa325a5559393d3283c9af3d01 (opens in a new tab)
- git.kernel.org/stable/c/8fd56ad6e7c90ac2bddb0741c6b248c8c5d56ac8 (opens in a new tab)
- git.kernel.org/stable/c/9340385468d056bb700b8f28df236b81fc86a079 (opens in a new tab)
- git.kernel.org/stable/c/aabe47cf5ac5e1db2ae0635f189d836f67024904 (opens in a new tab)
- lists.debian.org/debian-lts-announce/2025/03/msg00001.html (opens in a new tab)
- lists.debian.org/debian-lts-announce/2025/03/msg00002.html (opens in a new tab)