Vulnerability · Published Oct 20, 2026 · Assigned by GitHub_M
CVE-2026-112934filelock: SoftReadWriteLock holder refresh writes through a hard link and hangs on a named pipe that another local user renames over its record
Medium 6.1
In plain English
A medium-severity security flaw in filelock from tox-dev. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.2% (higher than 14% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Official description
filelock is a platform-independent file lock for Python. From 4.0.0 until 4.2.1, SoftReadWriteLock refreshes holder records by name, allowing another local user with rename access to the lock directory to replace a record with a named pipe and stall the lock, or under a permissive hard-link policy to link a reachable target file and cause the lock user to write through it. This issue is fixed in version 4.2.1.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian:12 | python-filelock | no fix listed | DEBIAN-CVE-2026-112934 |
| Debian:13 | python-filelock | no fix listed | DEBIAN-CVE-2026-112934 |
| Debian:14 | python-filelock | no fix listed | DEBIAN-CVE-2026-112934 |
| PyPI | filelock | 4.2.1 | GHSA-fj95-fr6c-h845 |
| Ubuntu:26.04:LTS | python-filelock | no fix listed | UBUNTU-CVE-2026-112934 |
| Ubuntu:26.10 | python-filelock | no fix listed | UBUNTU-CVE-2026-112934 |
Affected products (as reported)
Weakness: CWE-62 · Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:H
References
- https://github.com/tox-dev/filelock/security/advisories/GHSA-fj95-fr6c-h845 x_refsource_CONFIRM
- https://github.com/tox-dev/filelock/pull/842 x_refsource_MISC
- https://github.com/tox-dev/filelock/commit/bfa066d65a1ba9106f86ee9d027f7588b9c77e03 x_refsource_MISC
- https://github.com/tox-dev/filelock/releases/tag/4.2.1 x_refsource_MISC