CVE-2026-112939
filelock: SoftFileLock removes a live holder's marker when another user forges the PID in a writable marker
CVSS Score
4.7
EPSS Score
0.0%
EPSS Percentile
0th
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.
| CWE | CWE-345 |
| Vendor | tox-dev |
| Product | filelock |
| Published | Oct 20, 2026 |
| Last Updated | Oct 20, 2026 |
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CVSS v3 Breakdown
CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:H/A:N Attack Vector
Local
Attack Complexity
High
Privileges Required
Low
User Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
High
Availability
None
Affected Versions
tox-dev / filelock
>= 3.22.0, < 4.2.1
References
github.com: https://github.com/tox-dev/filelock/security/advisories/GHSA-rfpc-qcw5-3pc4 github.com: https://github.com/tox-dev/filelock/pull/836 github.com: https://github.com/tox-dev/filelock/commit/eeceaa846cbe4df72718d94c8371ca1ab8f5b3cc github.com: https://github.com/tox-dev/filelock/releases/tag/4.2.1