CVE-2026-112935
Medium
Description
filelock is a platform-independent file lock for Python. From 3.22.0 until 4.2.1, SoftFileLock can break a stale marker after an attacker frees its own marker following the stale read, an honest contender creates a live successor on the reused inode, and the successor's modification time is not newer than the saved observation, causing the live marker to be removed and two holders to be admitted. This issue is fixed in version 4.2.1.
SeverityMedium
CVSS4.7
Exploit probability—
ProductTox-dev Filelock
PublishedOct 20, 2026
First seenOct 20, 2026
Weakness typeCWE-367CWE-367
How to fix
Update
- tox-dev filelock4.2.1 or later
- filelock4.2.1 or later
Affected products
| Product | Affected versions | Fixed in |
|---|---|---|
| tox-dev filelock | 3.22.0 ≤ v < 4.2.1 | 4.2.1 |
| filelockPyPI | 3.22.0 ≤ v ≤ 4.2.0 | 4.2.1 |
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