poetry · filelock: SoftFileLock removes a live holder's marker when another user forges the PID in a writable marker
Affects poetrySource GCVE Database
Not known to be exploited · CVSS 4.7 Medium : upgrade to 2.5.1_1 when convenient.
Data as of 30 Oct 2026, 08:29 UTC
- Patch
- Available – fixed in 2.5.1_1
CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:H/A:NExploitation evidence
Disclosed: evidence found.
CVE published 20 Oct 2026
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
Upgrade poetry to 2.5.1_1.
Affected software
| Product | Affected | Fixed in |
|---|---|---|
Homebrewpoetrypkg:brew/poetryOther threats | Affected
| Fixed in
|
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 2.5.1_1. Users should upgrade to this version or later to resolve the vulnerability. Until patched, avoid setting group or other write permissions on lock marker files and ensure directories containing lock files are sticky or otherwise restrict marker file removal. Do not rely on soft file locks in environments where untrusted local users can write marker files.
Description
A vulnerability in filelock versions 3.22.0 through 4.2.0 allows a local user with write access to a lock marker file (but not removal rights) to forge the process ID in the marker. This causes the lock to be incorrectly considered stale, enabling two processes to simultaneously hold the lock and write to the protected resource without error. The issue arises when the marker file is group- or other-writable, typically due to permissive file modes or umask settings in sticky or restricted directories. The vulnerability has medium severity with a CVSS score of 4.7.
References
- github.com/tox-dev/filelock/security/advisories/GHSA-rfpc-qcw5-3pc4 (opens in a new tab)
- nvd.nist.gov/vuln/detail/CVE-2026-112939 (opens in a new tab)
- github.com/tox-dev/filelock/pull/836 (opens in a new tab)
- github.com/tox-dev/filelock/commit/eeceaa846cbe4df72718d94c8371ca1ab8f5b3cc (opens in a new tab)
- github.com/tox-dev/filelock (opens in a new tab)
- github.com/tox-dev/filelock/releases/tag/4.2.1 (opens in a new tab)