GHSA-wfhq-q4j2-c37m: filelock (CVE-2026-112941)

Package	Ecosystem	Affected	Fixed in
filelock	PyPI	>=4.1.0, <4.2.1	4.2.1

Machine-written summary

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

Affected: the PyPI package filelock, versions 4.1.0 up to but not including 4.2.1 (fixed in 4.2.1). A local user who can write the directory holding a SoftReadWriteLock path, or who created the lock's .rw tree first in a sticky directory such as /tmp, can swap in a tree whose gen or holders entry is a symbolic link into another directory. A long-running process that has already passed the one-time check then creates, renames and deletes lock-record files in that directory with its own privileges, with no race needed. Upgrade to filelock 4.2.1.

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
3.3	Low	3.1	CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N	CNA (GitHub_M)

CISA KEV Not listed.
EPSS 0.0013, the 2nd percentile, on 5 Nov 2026: FIRST’s estimate of the chance of exploitation in the next 30 days.

Timeline

31 Oct 2026, 14:07 UTC First seen by agentprime
31 Oct 2026, 14:07 UTC Confirmed by OSV

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.