Bug 2567720 (CVE-2026-112913)

Summary: CVE-2026-112913 filelock: filelock: Denial of service via pre-created SQLite side files
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
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Priority: low    
Version: unspecifiedKeywords: Security
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OS: Linux   
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A flaw was found in filelock. When a lock database is placed in a shared directory writable by other local users on Windows, an attacker can create crafted SQLite side files adjacent to the database. This manipulation causes subsequent lock acquisition attempts to fail immediately, resulting in a denial of service (DoS). Under specific conditions, this behavior may also trigger SQLite recovery to delete an arbitrary file accessible to the user acquiring the lock.
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Description OSIDB Bzimport 2026-11-05 22:20:39 UTC 
filelock is a platform-independent file lock for Python. From 3.20.4 until 4.2.1, ReadWriteLock and AsyncReadWriteLock on Windows use _connect to attach SQLite to the lock database by pathname, allowing another local account that can create adjacent names to place a database-wal or database-journal side file before acquisition. An undeletable WAL file makes each read or write acquisition fail immediately with sqlite3.OperationalError regardless of timeout. Separately, when the database contains at least one table, a hot journal that grants the lock account modify rights can cause SQLite recovery to delete a file named by that journal only when the lock account has permission to delete the target. The issue requires a directory writable by another account, such as a shared Windows temporary directory, and does not affect private directories. This issue is fixed in version 4.2.1.