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CVE-2026-112939VulnerabilityPublished

lexicon · filelock: SoftFileLock removes a live holder's marker when another user forges the PID in a writable marker

Affects lexiconSource GCVE Database

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Authoritative record:CVE-2026-112939· Medium 4.7

Not known to be exploited · CVSS 4.7 Medium : upgrade to 3.25.2_5 when convenient.

Data as of 30 Oct 2026, 07:32 UTC

CVSS 3.1 base score
4.7Medium
How severe the flaw is on the 0–10 CVSS scale.
Patch
Available – fixed in 3.25.2_5
CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:H/A:N

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 20 Oct 2026

  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

Upgrade lexicon to 3.25.2_5.

Affected software

ProductAffectedFixed in
Homebrewlexiconpkg:brew/lexiconOther threatsAffected
  • >=3.23.2_4 <3.25.2_5
Fixed in
  • 3.25.2_5

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

A fix is available in filelock version 3.25.2_5. Users should upgrade to this version or later to remediate the vulnerability. The issue arises only when the marker file is created or modified with group or other write permissions; using a restrictive umask (such as 022) or avoiding explicit permissive modes on the marker file can reduce exposure. Additionally, ensuring that the lock directory and its ancestors are owned by the user or root and are not writable by others or are sticky can help prevent unauthorized marker file modifications. No other specific mitigations are required once patched.

Description

A vulnerability in filelock versions 3.22.0 through 3.25.2_5 allows a local user with write access to a lock marker file (but without permission to remove it) to forge the process ID recorded in the marker. This causes another process that checks the marker to incorrectly consider the lock stale and remove the live marker, resulting in two processes simultaneously holding the lock and potentially corrupting the protected resource. The issue arises when the marker file is created or modified with group or other write permissions, such as with an explicit permissive mode or a lax umask in a sticky or non-removable directory. The vulnerability has a CVSS 3.1 score of 4.7 (Medium) and requires local access with low privileges and high attack complexity.

References

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