CVE-2026-112906 filelock: SoftFileLock evicts a fresh lock file whose watched age another local user's pre-dated file passed on through inode reuse
- Exploited in the wild
- Not known
- Fix
- Available
What is CVE-2026-112906?
CVE-2026-112906 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, SoftFileLock versions from 4.1.0 can reuse a stale observation when an attacker pre-dates and removes its own marker, at least two lock-user processes are waiting, coarse or matching modification times preserve the observation, and an honest contender creates a fresh marker on the reused inode, causing that live marker to be removed as stale. This issue is fixed in version 4.2.1.
Which versions are affected by CVE-2026-112906?
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-2026-112906?
Upgrade filelock to 4.2.1 or later.
Is CVE-2026-112906 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-112906 exists.
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-2026-112906, ECHO-a240-adbd-8056, GHSA-2g95-wg33-c5x2, UBUNTU-CVE-2026-112906.