Incorrect permissions on Windows lock files in Python filelock
Key facts
- Attack vector
- Local
- Privileges required
- Low
- User interaction
- None
- Attack complexity
- Low
- Impact type
- —
- Confidentiality · integrity · availability
- Low · Low · Low
- Fix status
- Partial Red Hat: 1 without a fix
Attack profile from CVSS 3.1 · CNA. Fix status from CNA, GitHub and Red Hat.
Summary
filelock versions from 3.10.0 before 4.2.1 on Windows ignore the mode argument for WindowsFileLock files and the ReadWriteLock SQLite database, so those files inherit the parent directory's inheritable ACL (CWE-732). A local account with inherited access can read holder metadata or the lock database, modify them where the ACL permits writes, or take the byte-range lock after release to delay later acquisitions. UnixFileLock is not affected, and mutual exclusion between cooperating processes still holds.
Written with Claude Haiku 5.5 from the sources below · 2026-11-06
Description from the CNA
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.
Why it matters now
SSVC decision points
Not available: CISA has not published SSVC decision points for this record.
Affected products
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| tox-dev | filelock | 3.10.0 to before 4.2.1 | 4.2.1 | Patch available | CNA |
| — | filelock (PyPI) | 3.10.0 to before 4.2.1 | 4.2.1 | Patch available | GHSA-8mx5-7m5m-r77g |
- filelock Vendortox-dev Affected 3.10.0 to before 4.2.1 Fixed in 4.2.1 Patch available CNA
- filelock (PyPI) Vendor— Affected 3.10.0 to before 4.2.1 Fixed in 4.2.1 Patch available GHSA-8mx5-7m5m-r77g
Remediation
Upgrade the filelock package from tox-dev and on PyPI to version 4.2.1, which fixes the flaw. Red Hat rates this Moderate and lists Red Hat OpenShift AI (RHOAI) as affected without a fix, with no plan available.
Written with Claude Haiku 5.5 from the sources below · 2026-11-06
- Fix · CNA filelock (tox-dev) Fixed in 4.2.1
- Fix · GHSA-8mx5-7m5m-r77g filelock (PyPI) Fixed in 4.2.1 Advisory →
Vendor assessments
Red Hat
Red Hat rating: Moderate. Red Hat's page for this CVE →
| Product | Status | Plan or fix |
|---|---|---|
| Red Hat OpenShift AI (RHOAI) | Affected | No fix yet: Fix deferred |
Timeline
- 2026-11-05 Threatist record created from CVE-2026-112910
- 2026-11-06 Affected versions changed · Red Hat
- 2026-11-06 CVSS score added · Red Hat
References
Other 6
- https://github.com/tox-dev/filelock/security/advisories/GHSA-8mx5-7m5m-r77g
- https://github.com/tox-dev/filelock/pull/835
- https://github.com/tox-dev/filelock/commit/72786d41aa25159ad28c1bcf4291738b135b2c6c
- https://github.com/tox-dev/filelock/commit/e1e825b1992f69fb6b346dc395d5ae4893536c0a
- https://github.com/tox-dev/filelock/releases/tag/4.2.1
- https://github.com/tox-dev/filelock
More tox-dev vulnerabilities
- TI-2026-76862 Symlink race in filelock ReadWriteLock lets attackers overwrite files CVSS 3.1HIGH 7.1
- TI-2026-76853 filelock soft locks adopt directories created by other local users CVSS 3.1MEDIUM 6.3
- TI-2026-76859 Symlink following in filelock ReadWriteLock redirects SQLite database CVSS 3.1MEDIUM 6.1
- TI-2026-76857 Unsafe holder record refresh in filelock SoftReadWriteLock CVSS 3.1MEDIUM 6.1
- TI-2026-76852 filelock UnixFileLock truncates files placed on the lock path CVSS 3.1MEDIUM 6.1
- TI-2026-76856 Crafted lock database makes filelock ReadWriteLock acquisitions hang CVSS 3.1MEDIUM 5.5
Sources
- CVE-2026-112910 · CVE Program
- CVE-2026-112910 · NVD
- FIRST EPSS
- CVE-2026-112910 · Red Hat security data · CC BY 4.0
This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences