Medium severity · published Oct 20, 2026
CVE-2026-112936
filelock: ReadWriteLock follows a symlink at the lock path into SQLite
6.1
CVSS
0.2%
EPSS
No
On KEV
Description
filelock is a platform-independent file lock for Python. From 3.20.4 until 4.0.9, ReadWriteLock and AsyncReadWriteLock versions from 3.20.4 resolve the lock path and pass it to SQLite without rejecting a final symbolic link, allowing another local user who can create names in the lock directory to redirect database creation and locking or split mutual exclusion between targets. This issue is fixed in version 4.0.9.
CVSS vector
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:L
Attack vector
Local
Complexity
Low
Privileges
Low
User interaction
None
Confidentiality
None
Integrity
High
Availability
Low
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.2% · higher than 14% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
FI
filelock · tox-dev
>= 3.20.4, < 4.0.9 · source: vendor, NVD
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-112936
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-112936
Patch
https://github.com/tox-dev/filelock/commit/4d45e83caf7e31f9a12fb44526bdc07f70114f04
Release Notes
https://github.com/tox-dev/filelock/releases/tag/4.0.9
Exploit
https://github.com/tox-dev/filelock/security/advisories/GHSA-j8f7-rjxc-mr56
More from filelock
7.1
CVE-2026-112940
filelock ReadWriteLock: SQLite reopens the lock database by name, so a planted symlink or journal file makes the lock user's process overwrite or unlink its own files
6.5
CVE-2025-68146
filelock has TOCTOU race condition that allows symlink attacks during lock file creation
6.3
CVE-2026-112911
filelock: StrictSoftFileLock and SoftReadWriteLock adopt a protocol directory another user created first, losing mutual exclusion
6.1
CVE-2026-112937
filelock: ReadWriteLock on the hard-link route deletes any directory another user renames onto its .filelock-* link directory name
6.1
CVE-2026-112934
filelock: SoftReadWriteLock holder refresh writes through a hard link and hangs on a named pipe that another local user renames over its record