Vulnerability · Published Oct 20, 2026 · Assigned by GitHub_M
CVE-2026-112906filelock: SoftFileLock evicts a fresh lock file whose watched age another local user's pre-dated file passed on through inode reuse
Medium 4.7
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 6% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Official description
filelock is a platform-independent file lock for Python. From 4.1.0 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.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian:12 | python-filelock | no fix listed | DEBIAN-CVE-2026-112906 |
| Debian:13 | python-filelock | no fix listed | DEBIAN-CVE-2026-112906 |
| Debian:14 | python-filelock | no fix listed | DEBIAN-CVE-2026-112906 |
| PyPI | filelock | 4.2.1 | GHSA-2g95-wg33-c5x2 |
| Ubuntu:26.04:LTS | python-filelock | no fix listed | UBUNTU-CVE-2026-112906 |
| Ubuntu:26.10 | python-filelock | no fix listed | UBUNTU-CVE-2026-112906 |
Affected products (as reported)
Weakness: CWE-694 · Vector: CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:H/A:N
References
- https://github.com/tox-dev/filelock/security/advisories/GHSA-2g95-wg33-c5x2 x_refsource_CONFIRM
- https://github.com/tox-dev/filelock/commit/740ff666b62a88496c8d7394e4e6230605e4d62b x_refsource_MISC
- https://github.com/tox-dev/filelock/releases/tag/4.2.1 x_refsource_MISC