CVE-2026-112915: filelock DoS — Exploit & Fix

Description

filelock is a platform-independent file lock for Python. From 3.20.4 until 4.2.1, ReadWriteLock can open a crafted SQLite lock database without bounding schema and query work, allowing another local user who can replace the database to make acquisition stall or hang; versions from 3.20.4 expose this on initial per-instance opening, and versions from 3.30.0 repeat the exposure on every acquisition. This issue is fixed in version 4.2.1.

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CVSS v3.1 Score

5.5

MEDIUM

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

EPSS — Exploit Prediction

0.0022

Probability of exploitation

0.12%

Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

Weakness Type (CWE)

CWE-400 Uncontrolled Resource Consumption

Affected Products

Vendor	Product	Versions
tox-dev	filelock	3.20.4 — 4.2.1

References

Advisories & Patches

https://github.com/tox-dev/filelock/commit/5e3f2ec0c5fb17cb2635b60b2b68bc63ab81ca2d https://github.com/tox-dev/filelock/pull/834 https://github.com/tox-dev/filelock/security/advisories/GHSA-cwqr-hh33-gh44 https://github.com/tox-dev/filelock/security/advisories/GHSA-cwqr-hh33-gh44

Exploits

https://github.com/tox-dev/filelock/security/advisories/GHSA-cwqr-hh33-gh44 https://github.com/tox-dev/filelock/security/advisories/GHSA-cwqr-hh33-gh44

Other References

https://github.com/tox-dev/filelock/releases/tag/4.2.1

Frequently Asked Questions

What is CVE-2026-112915? +

filelock is a platform-independent file lock for Python. From 3.20.4 until 4.2.1, ReadWriteLock can open a crafted SQLite lock database without bounding schema and query work, allowing another local user who can replace the database to make acquisition stall or hang; versions from 3.20.4 expose this on initial per-instance opening, and versions from 3.30.0 repeat the exposure on every acquisition. This issue is fixed in version 4.2.1. It has a CVSS v3.1 base score of 5.5 (MEDIUM).

How severe is CVE-2026-112915? +

CVE-2026-112915 has a CVSS v3.1 score of 5.5 out of 10, rated MEDIUM. This is a medium-severity vulnerability that should be remediated as part of regular maintenance. The EPSS score is 0.0022, placing it in the 0th percentile for exploitation probability.

What products are affected by CVE-2026-112915? +

CVE-2026-112915 affects products from tox-dev, specifically: filelock. Check the affected products table above for specific version ranges.

How do I check if I'm vulnerable to CVE-2026-112915? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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CVE-2026-112915