Vulnerability in Tox-Dev Filelock
CVE-2026-22701
filelock is a platform-independent file lock for Python. Prior to version 3.20.3, a TOCTOU race condition vulnerability exists in the SoftFileLock implementation of the filelock package. An attacker with local filesystem access and permission to create symlinks can exploit a race condition between the permission validation and file creation to cause lock operations to fail or behave unexpectedly. The vulnerability occurs in the _acquire() method between raise_on_not_writable_file() (permission check) and os.open() (file creation). During this race window, an attacker can create a symlink at the lock file path, potentially causing the lock to operate on an unintended target file or leading to denial of service. This issue has been patched in version 3.20.3.
Published · last modified .
CVSS v3 metric
CVSS v3 base score 5.3 (Medium). Vector: CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:L/A:H.
EPSS exploit prediction
EPSS: 0.001 (2.1th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 2nd percentile — 2.1% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.001 · newest: 0.001 · change: +0.000
Affected products
- Tox-Dev Filelock — versions < 3.20.3
Weakness classification (CWE)
References
Frequently asked questions
- What is CVE-2026-22701?
- CVE-2026-22701 is a medium-severity vulnerability in Tox-Dev Filelock, classified under Improper Link Resolution Before File Access. CVSS score: 5.3/10. Published 2026-01-10.
- How severe is CVE-2026-22701?
- Medium severity. CVSS v3 base score is 5.3 out of 10.