GHSA-8mx5-7m5m-r77g: filelock (CVE-2026-112910)

Package	Ecosystem	Affected	Fixed in
filelock	PyPI	>=3.10.0, <4.2.1	4.2.1

Machine-written summary

Summary written by Claude Haiku from the source advisory. Not reviewed by a person.

Affected versions are filelock 3.10.0 through 4.2.0 on Windows, where the `mode` argument is ignored, so a lock file or ReadWriteLock database created with mode 0o600 inherits the containing directory's access list. A local account that other people's directory grants access to new files can read the files, hold the byte-range lock to make the owner's acquire calls wait or time out, and, where the directory grants modify access, write to them; the attacker needs a logon on the same host and an ordinary account. Upgrade to filelock 4.2.1, which fixes the issue.

Written 31 Oct 2026.

Not analysed yet

We haven’t published our analysis of this Advisory yet. Once a person has reviewed it, this page will say what’s vulnerable, what has to be true for your app to be affected, and how to check.

Severity and exploitation

Score	Rating	CVSS	Vector	Source
5.3	Medium	3.1	CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:L	CNA (GitHub_M)

CISA KEV Not listed.
EPSS No score.

Timeline

31 Oct 2026, 14:07 UTC First seen by agentprime
31 Oct 2026, 14:07 UTC Confirmed by OSV
5 Nov 2026, 21:47 UTC Confirmed by the CVE List
5 Nov 2026, 22:17 UTC Confirmed by NVD

Sources

Facts on this page come from the GitHub Advisory Database (CC-BY 4.0), OSV and the other sources listed, as published. We don’t reproduce full advisory descriptions, which can contain exploit code.