Bug 2567790 (CVE-2026-112907)

Summary:	CVE-2026-112907 filelock: filelock: Denial of Service via Windows opportunistic lock on lock markers
Product:	[Other] Security Response	Reporter:	OSIDB Bzimport <bzimport>
Component:	vulnerability	Assignee:	Product Security DevOps Team <prodsec-dev>
Status:	NEW ---	QA Contact:
Severity:	low	Docs Contact:
Priority:	low
Version:	unspecified	Keywords:	Security
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Hardware:	All
OS:	Linux
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Doc Text:	A flaw was found in filelock. On Windows systems, soft lock implementations perform file operations that wait indefinitely when another process holds an opportunistic lock (oplock) on an unheld lock marker file. A local user with read access to the marker file can request an oplock and leave break requests unanswered, causing subsequent lock acquisition attempts to stall past configured timeouts. This issue allows an attacker to cause a Denial of Service (DoS) by preventing applications from obtaining required locks.	Story Points:	---
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oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---	Target Upstream Version:
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Description OSIDB Bzimport 2026-11-05 22:26:18 UTC

filelock is a platform-independent file lock for Python. From 3.22.0 until 4.2.1, soft lock classes on Windows read an existing marker with _read_lock_file and remove a stale marker through break_lock_file using pathname operations that wait for an oplock break. Another local account with read access to an unheld marker can keep a Level 1 or batch oplock unanswered, causing SoftFileLock.acquire and related async or fallback locks to wait beyond timeout, blocking=False, and cancel_check. A stale marker under the oplock cannot be broken, but mutual exclusion remains intact and no file other than the marker is accessed. This issue is fixed in version 4.2.1.