CVE-2026-112910

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

Published Nov 5, 2026 CVSS 3.1 · 5.3 Medium EPSS < 1% KEV · Not listed
Description
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.

Remediation

No solution or workaround provided in the CVE record

Tracking

Sign in to view the affected projects.

Advisories

Source ID Title
Github GHSA Github GHSA GHSA-8mx5-7m5m-r77g filelock: WindowsFileLock ignores mode: a 0o600 lock file and the ReadWriteLock database inherit the directory ACL
History
Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'poc', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

Type Values Removed Values Added
First Time appeared Tox-dev
Tox-dev filelock
Vendors & Products Tox-dev
Tox-dev filelock
Type Values Removed Values Added
Description 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.
Title filelock: WindowsFileLock ignores mode: a 0o600 lock file and the ReadWriteLock database inherit the directory ACL
Weaknesses CWE-732
References
Metrics cvssV3_1

{'score': 5.3, 'vector': 'CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:L'}

Weaknesses

Sources

Status
PUBLISHED
Assigner
GitHub_M
Published
Updated
Nov 9, 2026, 6:50 PM
Reserved
Oct 19, 2026, 8:16 PM
Status
Awaiting Analysis
Published
Nov 5, 2026, 10:17 PM
Modified
Nov 9, 2026, 7:16 PM
Severity
Moderate
Public date
Nov 5, 2026, 9:47 PM