CVE-2026-112908

NameCVE-2026-112908
Descriptionfilelock is a platform-independent file lock for Python. From version 3.30.0 until version 4.2.1,  StrictSoftFileLock  and  AsyncStrictSoftFileLock  on POSIX systems create coordination and claim directories without applying the caller’s restrictive lock mode. A permissive umask or inherited default ACL can leave these directories writable by another local user, allowing that user to delete an active holder’s claims. Another authorized process can then acquire the lock while the original holder remains in its critical section. An attacker can also plant malformed claims to prevent acquisition. This issue is fixed in version 4.2.1.
SourceCVE (at NVD; CERT, ENISA, LWN, oss-sec, fulldisc, Debian ELTS, Red Hat, Ubuntu, Gentoo, SUSE bugzilla/CVE, GitHub advisories/code/issues, web search, more)

Vulnerable and fixed packages

The table below lists information on source packages.

Source PackageReleaseVersionStatus
python-filelock (PTS)bookworm3.9.0-1+deb12u1vulnerable
trixie3.18.0-1+deb13u1vulnerable
forky4.1.1-1vulnerable
sid4.2.8-1fixed

The information below is based on the following data on fixed versions.

PackageTypeReleaseFixed VersionUrgencyOriginDebian Bugs
python-filelocksource(unstable)4.2.2-1

Notes

https://github.com/tox-dev/filelock/pull/839
Fixed by: https://github.com/tox-dev/filelock/commit/bfa066d65a1ba9106f86ee9d027f7588b9c77e03 (4.2.1)

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