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VulnerabilityPublished Updated

CVE-2025-21944: Linux kernel · ksmbd: fix bug on trap in smb2_lock

Source GCVE Database

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Not known to be exploited · CVSS 5.5 Medium.

Data as of 30 Oct 2026, 01:24 UTC

CVSS 3.1 base score
5.5Medium
How severe the flaw is on the 0–10 CVSS scale.
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 1 Apr 2025

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponized: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq 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 The flaw involves incorrect handling of lock flags when the lock count is greater than one, causing the system to use outdated flag values.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

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