CVE-2026-112939CWE-345

CVE-2026-112939

Medium · published October 20, 2026

CVSS v3.1
4.7
EPSS
0%
Percentile
3.0
In the wild
Unconfirmed
What it is

filelock is a platform-independent file lock for Python. From 3.22.0 until 4.2.1, SoftFileLock can trust a forged process identifier in a marker that an attacker can modify but cannot remove, allowing an authorized contender such as another process of the holder's account or root to act as a confused deputy, remove the live marker, and admit another holder. This issue is fixed in version 4.2.1.

The record
Technical detail
CVSS v3.1
4.7 · MEDIUM
Vector
CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:H/A:N
CVSS v4.0
Not supplied
EPSS
0.00140 · 3.0th percentile
Weakness
CWE-345 · Insufficient Verification of Data Authenticity
Published
2026-10-20T19:17Z
Affected products (1)
ProductVersionsFixed in
tox-dev/filelock≥ 3.22.0, < 4.2.14.2.1
References (5)
https://github.com/tox-dev/filelock/commit/eeceaa846cbe4df72718d94c8371ca1ab8f5b3cc · [email protected]https://github.com/tox-dev/filelock/pull/836 · [email protected]https://github.com/tox-dev/filelock/releases/tag/4.2.1 · [email protected]https://github.com/tox-dev/filelock/security/advisories/GHSA-rfpc-qcw5-3pc4 · [email protected]https://github.com/tox-dev/filelock/security/advisories/GHSA-rfpc-qcw5-3pc4 · 134c704f-9b21-4f2e-91b3-4a467353bcc0
EPSS history
Timeline
  • 22 OCT 03:29Z
    EPSS moved — → 0%
    epss
  • 20 OCT 14:38Z
    filelock: SoftFileLock removes a live holder's marker when another user forges the PID in a writable marker
    cvelistv5
  • 20 OCT 14:38Z
    filelock: SoftFileLock removes a live holder's marker when another user forges the PID in a writable marker
    cvelistv5