CVE-2025-21812: Linux kernel · ax25: rcu protect dev->ax25_ptr
Source GCVE Database
Not known to be exploited · CVSS 7.8 High.
Data as of 30 Oct 2026, 01:14 UTC
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:HExploitation evidence
Disclosed: evidence found.
CVE published 27 Feb 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 has been implemented in the Linux kernel by removing the ax25 RTNL dependency in ax25_setsockopt(), resolving the locking dependency and use-after-free issues. Users and administrators should update to the fixed kernel versions once available. Patch status is not explicitly confirmed in the provided data, so check the official Linux kernel advisories or vendor updates for the fixed versions and apply them promptly.
Description
CVE-2025-21812 is a high-severity use-after-free vulnerability in the Linux kernel's ax25 networking code. It involves a locking dependency issue between sk_lock-AF_AX25 and rtnl_mutex locks, which can lead to deadlocks and potential memory corruption. The issue was identified by syzbot and relates to improper protection of the dev->ax25_ptr pointer. The vulnerability has been resolved by removing the ax25 RTNL dependency in ax25_setsockopt().
References
- nvd.nist.gov/vuln/detail/CVE-2025-21812 (opens in a new tab)
- git.kernel.org/stable/c/2802ed4ced27ebd474828fc67ffd7d66f11e3605 (opens in a new tab)
- git.kernel.org/stable/c/7705d8a7f2c26c80973c81093db07c6022b2b30e (opens in a new tab)
- git.kernel.org/stable/c/8937f5e38a218531dce2a89fae60e3adcc2311e1 (opens in a new tab)
- git.kernel.org/stable/c/95fc45d1dea8e1253f8ec58abc5befb71553d666 (opens in a new tab)
- git.kernel.org/stable/c/c2531db6de3c95551be58878f859c6a053b7eb2e (opens in a new tab)
- lists.debian.org/debian-lts-announce/2025/03/msg00028.html (opens in a new tab)