CVE-2026-112910

filelock: WindowsFileLock ignores mode: a 0o600 lock file and the ReadWriteLock database inherit the directory ACL

publishedCWE-732

filelock is a platform-independent file lock for Python. From 3.10.0 until 4.2.1, filelock on Windows ignores the mode argument for WindowsFileLock files and the ReadWriteLock SQLite database. A lock created with mode=0o600 receives the parent directory's inheritable ACL because _open_non_reparse_fd and _nt_open do not create an owner-only security descriptor. Another local account with inherited access can read holder metadata or the lock database, modify those files where the ACL permits writes, or take the byte-range lock after release and delay later acquisitions. UnixFileLock is not affected, and mutual exclusion between cooperating processes continues to hold. This issue is fixed in version 4.2.1.

Technical severity5.3 mediumCVSS 3.1 · CNA: GitHub_M

Published2026-11-05Source updated 2026-11-05

Collected2026-11-052 attributed sources

Fixes and workarounds

Fix

filelock (PyPI): OSV reports a fixed version 4.2.1. Check the advisory for supported release branches.

Source: OSV GHSA-8mx5-7m5m-r77g

Affected products and versions

Affected products, source version ranges and reporting authorities
Product	Versions	Authority
filelock tox-dev	>= 3.10.0, < 4.2.1 (affected)	CNA: GitHub_M
filelock `filelock` PyPI	3.10.0 (affected, PyPI) 3.10.1 (affected, PyPI) 3.10.2 (affected, PyPI) 3.10.3 (affected, PyPI) 3.10.4 (affected, PyPI) 3.10.5 (affected, PyPI) 3.10.6 (affected, PyPI) 3.10.7 (affected, PyPI) 3.11.0 (affected, PyPI) 3.12.0 (affected, PyPI) 3.12.1 (affected, PyPI) 3.12.2 (affected, PyPI) 3.12.3 (affected, PyPI) 3.12.4 (affected, PyPI) 3.13.0 (affected, PyPI) 3.13.1 (affected, PyPI) 3.13.2 (affected, PyPI) 3.13.3 (affected, PyPI) 3.13.4 (affected, PyPI) 3.14.0 (affected, PyPI) 3.15.0 (affected, PyPI) 3.15.1 (affected, PyPI) 3.15.2 (affected, PyPI) 3.15.3 (affected, PyPI) 3.15.4 (affected, PyPI) 3.16.0 (affected, PyPI) 3.16.1 (affected, PyPI) 3.17.0 (affected, PyPI) 3.18.0 (affected, PyPI) 3.19.1 (affected, PyPI) 3.20.0 (affected, PyPI) 3.20.1 (affected, PyPI) 3.20.2 (affected, PyPI) 3.20.3 (affected, PyPI) 3.20.4 (affected, PyPI) 3.21.0 (affected, PyPI) 3.21.1 (affected, PyPI) 3.21.2 (affected, PyPI) 3.22.0 (affected, PyPI) 3.23.0 (affected, PyPI) 3.24.0 (affected, PyPI) 3.24.1 (affected, PyPI) 3.24.2 (affected, PyPI) 3.24.3 (affected, PyPI) 3.25.0 (affected, PyPI) 3.25.1 (affected, PyPI) 3.25.2 (affected, PyPI) 3.28.0 (affected, PyPI) 3.29.0 (affected, PyPI) 3.29.1 (affected, PyPI) 3.29.2 (affected, PyPI) 3.29.3 (affected, PyPI) 3.29.4 (affected, PyPI) 3.29.5 (affected, PyPI) 3.29.6 (affected, PyPI) 3.29.7 (affected, PyPI) 3.30.0 (affected, PyPI) 3.30.1 (affected, PyPI) 3.30.2 (affected, PyPI) 3.30.3 (affected, PyPI) 3.31.0 (affected, PyPI) 3.31.1 (affected, PyPI) 3.31.2 (affected, PyPI) 3.32.0 (affected, PyPI) 3.32.2 (affected, PyPI) 3.32.3 (affected, PyPI) 3.32.4 (affected, PyPI) 3.32.5 (affected, PyPI) 3.32.6 (affected, PyPI) 3.32.7 (affected, PyPI) 4.0.0 (affected, PyPI) 4.0.1 (affected, PyPI) 4.0.10 (affected, PyPI) 4.0.11 (affected, PyPI) 4.0.12 (affected, PyPI) 4.0.2 (affected, PyPI) 4.0.3 (affected, PyPI) 4.0.4 (affected, PyPI) 4.0.5 (affected, PyPI) 4.0.6 (affected, PyPI) 4.0.7 (affected, PyPI) 4.0.8 (affected, PyPI) 4.0.9 (affected, PyPI) 4.1.0 (affected, PyPI) 4.1.1 (affected, PyPI) 4.1.2 (affected, PyPI) 4.2.0 (affected, PyPI) Ecosystem version events: introduced 3.10.0; fixed 4.2.1 Source events (ECOSYSTEM) `[ { "introduced": "3.10.0" }, { "fixed": "4.2.1" } ]` Other versions: unaffected	OSV GHSA-8mx5-7m5m-r77g

Version ranges are source assertions. Check the vendor advisory and your installed configuration before determining exposure.

CVSS assessments

CVSS scores, vectors and reporting authorities
Version / score	Vector	Authority
3.1 / 5.3 medium	`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:L`	CNA: GitHub_M

Exploit evidence

No exploit evidence in collected sources. This is not proof of no exploitation.

References

https://github.com/tox-dev/filelock/security/advisories/GHSA-8mx5-7m5m-r77gCNA: GitHub_M · x_refsource_CONFIRM
https://github.com/tox-dev/filelock/pull/835CNA: GitHub_M · x_refsource_MISC
https://github.com/tox-dev/filelock/commit/72786d41aa25159ad28c1bcf4291738b135b2c6cCNA: GitHub_M · x_refsource_MISC
https://github.com/tox-dev/filelock/commit/e1e825b1992f69fb6b346dc395d5ae4893536c0aCNA: GitHub_M · x_refsource_MISC
https://github.com/tox-dev/filelock/releases/tag/4.2.1CNA: GitHub_M · x_refsource_MISC
https://github.com/advisories/GHSA-8mx5-7m5m-r77gOSV / GitHub Security Advisories · advisory
https://osv.dev/vulnerability/GHSA-8mx5-7m5m-r77gOSV / GitHub Security Advisories · osv

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