CVE-2026-112937 filelock: ReadWriteLock on the hard-link route deletes any directory another user renames onto its .filelock-* link directory name
- Exploited in the wild
- Not known
- Fix
- Available
What is CVE-2026-112937?
CVE-2026-112937 is a medium-severity vulnerability in tox-dev filelock, published on 20 Oct 2026.
Official description
filelock is a platform-independent file lock for Python. From 4.1.0 until 4.2.1, ReadWriteLock can remove a randomized .filelock-* private-hard-link directory during cleanup, allowing another local user with rename access in a non-sticky parent to observe a live name or forge a dead-owner sweep name and rename a sibling directory onto it for deletion. This issue is fixed in version 4.2.1.
Weakness: CWE-367
Which versions are affected by CVE-2026-112937?
2 open source packages ship an affected version, including filelock. It affects 1 product.
| Package | Affected | Fixed in |
|---|---|---|
filelock PyPI | From 4.1.0 | 4.2.1 |
filelock PyPI | From 4.1.0 | 4.2.1 |
Products include Tox-Dev Filelock.
How do I fix CVE-2026-112937?
Upgrade filelock to 4.2.1 or later.
Is CVE-2026-112937 being exploited?
There is no known exploitation of CVE-2026-112937 in the wild and no public exploit code.
Other vulnerabilities in tox-dev filelock
- CVE-2026-112940 filelock ReadWriteLock: SQLite reopens the lock database by name, so a planted symlink or journal file makes the lock user's process overwrite or unlink its own files
- CVE-2026-112911 filelock: StrictSoftFileLock and SoftReadWriteLock adopt a protocol directory another user created first, losing mutual exclusion
- CVE-2025-68146 filelock has TOCTOU race condition that allows symlink attacks during lock file creation
- CVE-2026-112909 filelock: UnixFileLock truncates and chmods any regular file another user renames or hard-links onto the lock path
- CVE-2026-112934 filelock: SoftReadWriteLock holder refresh writes through a hard link and hangs on a named pipe that another local user renames over its record
Sources
Also known as DEBIAN-CVE-2026-112937, ECHO-50ba-30e2-c806, GHSA-jqc4-5cvw-7w85, UBUNTU-CVE-2026-112937.