Vulnerability · Published Oct 20, 2026 · Assigned by GitHub_M
CVE-2026-112940filelock 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
High 7.1
In plain English
A high-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 9% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Official description
filelock is a platform-independent file lock for Python. From 3.20.4 until 4.2.1, ReadWriteLock let SQLite reopen the database and side files by name; on POSIX systems an attacker with rename access in a non-sticky parent can swap those names to cause overwrite or unlink operations, while a writable adjacent hot journal is additionally required for attacker-chosen content overwrites. 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-2026-112940 |
| Debian:13 | python-filelock | no fix listed | DEBIAN-CVE-2026-112940 |
| Debian:14 | python-filelock | no fix listed | DEBIAN-CVE-2026-112940 |
| PyPI | filelock | 4.2.1 | GHSA-v4x8-3wr5-3wq8 |
| Ubuntu:26.04:LTS | python-filelock | no fix listed | UBUNTU-CVE-2026-112940 |
| Ubuntu:26.10 | python-filelock | no fix listed | UBUNTU-CVE-2026-112940 |
Affected products (as reported)
Weakness: CWE-363 · Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:H
References
- https://github.com/tox-dev/filelock/security/advisories/GHSA-v4x8-3wr5-3wq8 x_refsource_CONFIRM
- https://github.com/tox-dev/filelock/pull/834 x_refsource_MISC
- https://github.com/tox-dev/filelock/commit/5e3f2ec0c5fb17cb2635b60b2b68bc63ab81ca2d x_refsource_MISC
- https://github.com/tox-dev/filelock/releases/tag/4.2.1 x_refsource_MISC