Description
filelock is a platform-independent file lock for Python. From 4.1.0 until 4.2.1, SoftFileLock can restore a stale marker by name after moving it aside, allowing another local user with rename access in a non-sticky lock directory to swap in a symbolic link and, on a runtime that follows the link and a same-filesystem target, make the lock user hard-link one of its files into the lock directory. This issue is fixed in version 4.2.1.
Affected products
tox-dev: filelock
References4
- github.com/tox-dev/filelock/security/advisories/GHSA-crv4-6mhj-… ExploitMitigationPatchVendor Advisory
- github.com/tox-dev/filelock/commit/740ff666b62a88496c8d7394e4e6… Patch
- github.com/tox-dev/filelock/pull/843 Patch
- github.com/tox-dev/filelock/releases/tag/4.2.1 Release Notes
Metrics
- CVSS 3.1
-
5.3
MEDIUM
Score source: CNA
CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:L/I:H/A:N - EPSS — exploit probability
- 0% percentile: 5 · as of 9 November 2026
- CWE
- CWE-363CWE-59
Could this be exploited in your environment?
A patch closes the known hole. A penetration test shows what an attacker can still reach — with proof.