Bug 2428442 (CVE-2026-22701)

Summary:	CVE-2026-22701 filelock: filelock Time-of-Check-Time-of-Use (TOCTOU) in SoftFileLock
Product:	[Other] Security Response	Reporter:	OSIDB Bzimport <bzimport>
Component:	vulnerability	Assignee:	Product Security DevOps Team <prodsec-dev>
Status:	NEW ---	QA Contact:
Severity:	medium	Docs Contact:
Priority:	medium
Version:	unspecified	CC:	alinfoot, anpicker, anthomas, aprice, bbrownin, bdettelb, bparees, carogers, caswilli, crizzo, dfreiber, dnakabaa, doconnor, drow, dtrifiro, dymurray, eglynn, ehelms, erezende, ggainey, gtanzill, haoli, hasun, hkataria, ibolton, jajackso, jburrell, jbuscemi, jcammara, jdobes, jfula, jjoyce, jkoehler, jmatthew, jmitchel, jmontleo, jneedle, joehler, jowilson, jsamir, jschluet, juwatts, jwong, kaycoth, kegrant, kgaikwad, koliveir, kshier, lball, lcouzens, lhh, ljawale, lphiri, luizcosta, mabashia, mburns, mgarciac, mhayden, mhulan, mskarbek, ngough, nmoumoul, nweather, nyancey, oezr, omaciel, ometelka, orabin, osousa, pbraun, pcreech, pgaikwad, ptisnovs, rbobbitt, rbryant, rchan, rjohnson, sdawley, sdoran, shvarugh, simaishi, slucidi, smallamp, smcdonal, sseago, stcannon, syedriko, teagle, tfister, thavo, tmalecek, ttakamiy, veshanka, vkumar, weaton, xdharmai, yguenane, zzhou
Target Milestone:	---	Keywords:	Security
Target Release:	---
Hardware:	All
OS:	Linux
Whiteboard:
Fixed In Version:		Doc Type:	---
Doc Text:	A Time-of-Check-Time-of-Use (TOCTOU) flaw has been discovered in the pypi filelock package. The TOCTOU race condition vulnerability exists in the SoftFileLock implementation of the filelock package. An attacker with local filesystem access and permission to create symlinks can exploit a race condition between the permission validation and file creation to cause lock operations to fail or behave unexpectedly. The vulnerability occurs in the _acquire() method between raise_on_not_writable_file() (permission check) and os.open() (file creation). During this race window, an attacker can create a symlink at the lock file path, potentially causing the lock to operate on an unintended target file or leading to denial of service.	Story Points:	---
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oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---	Target Upstream Version:
Embargoed:
Bug Depends On:	2429315, 2429316, 2429317, 2429321, 2429318, 2429319, 2429320
Bug Blocks:

Description OSIDB Bzimport 2026-01-10 07:01:43 UTC

filelock is a platform-independent file lock for Python. Prior to version 3.20.3, a TOCTOU race condition vulnerability exists in the SoftFileLock implementation of the filelock package. An attacker with local filesystem access and permission to create symlinks can exploit a race condition between the permission validation and file creation to cause lock operations to fail or behave unexpectedly. The vulnerability occurs in the _acquire() method between raise_on_not_writable_file() (permission check) and os.open() (file creation). During this race window, an attacker can create a symlink at the lock file path, potentially causing the lock to operate on an unintended target file or leading to denial of service. This issue has been patched in version 3.20.3.