CVE-2025-21944: Linux kernel · ksmbd: fix bug on trap in smb2_lock
Source GCVE Database
Not known to be exploited · CVSS 5.5 Medium.
Data as of 30 Oct 2026, 01:24 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 1 Apr 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
Until a fix is available, avoid exposing vulnerable kernel versions to untrusted SMB clients or restrict SMB access to trusted networks.
Description
CVE-2025-21944 is a medium-severity vulnerability in the Linux kernel's ksmbd component related to SMB2 locking. The flaw involves incorrect handling of lock flags when the lock count is greater than one, causing the system to use outdated flag values. This leads to a bug-on trap triggered by the locks_free_lock function during error handling.
References
- nvd.nist.gov/vuln/detail/CVE-2025-21944 (opens in a new tab)
- git.kernel.org/stable/c/11e0e74e14f1832a95092f2c98ed3b99f57797ee (opens in a new tab)
- git.kernel.org/stable/c/2b70e3ac79eacbdf32571f7af48dd81cdd957ca8 (opens in a new tab)
- git.kernel.org/stable/c/8994f0ce8259f812b4f4a681d8298c6ff682efaa (opens in a new tab)
- git.kernel.org/stable/c/dbcd7fdd86f77529210fe8978154a81cd479844c (opens in a new tab)
- git.kernel.org/stable/c/e26e2d2e15daf1ab33e0135caf2304a0cfa2744b (opens in a new tab)
- lists.debian.org/debian-lts-announce/2025/05/msg00045.html (opens in a new tab)