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OpenAdvisories
Medium · 5.3 CVE-2026-112914 EUVD-2026-105020GHSA-crv4-6mhj-j5jh

filelock: SoftFileLock stale-break restore follows a swapped-in symbolic link and hard-links a file of the user running the lock into the lock directory

Published Oct 20, 2026 · Updated Oct 21, 2026 · Assigned by GitHub_M

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

VendorProductAffectedFixed
tox-dev filelock >= 4.1.0, < 4.2.1 —

Fixed in Linux distributions

Distributions backport fixes, so the version that fixes this vulnerability differs per release — upgrade to at least the version shown. From the distributions' security trackers and advisories.

ReleasePackageFixed inAdvisory
Debian 14 python-filelock 4.2.8-1 —
Debian 13 python-filelock No fix yet —
Debian 12 python-filelock No fix yet —
ReleasePackageFixed inAdvisory
Ubuntu 26.10 python-filelock No fix yet —
Ubuntu 26.04 LTS python-filelock No fix yet —
Show 4 more (older releases, extended support, other products)
ReleasePackageFixed inAdvisory
Ubuntu Pro 24.04 LTS python-filelock No fix yet —
Ubuntu Pro 22.04 LTS python-filelock No fix yet —
Ubuntu Pro 20.04 LTS python-filelock No fix yet —
Ubuntu Pro 18.04 LTS python-filelock No fix yet —

Affected packages

EcosystemPackageAffectedFixedRecord
PyPI filelock >= 4.1.0, < 4.2.1 4.2.1 GHSA-crv4-6mhj-j5jh

References