Bug 2559600 (CVE-2026-98901)

Summary:	CVE-2026-98901 kernel: ksmbd: fix lease break and ack state handling
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:	akhatavk, aos-team-art-private, asdas, dpaolell, jdelft, jupierce, lgarciaa, mbiarnes, ppalepu, ppostler, prdhamdh, rhel-process-autobot, sghai, sidsharm, suppawar, vlaad, watson-tool-maintainers
Target Milestone:	---	Keywords:	Security
Target Release:	---
Hardware:	All
OS:	Linux
Whiteboard:
Fixed In Version:		Doc Type:	---
Doc Text:	A flaw was found in the Linux kernel's ksmbd module, an in-kernel Server Message Block (SMB) file sharing service. An authenticated remote client can cause a localized Denial of Service (DoS) or introduce file cache inconsistencies due to improper handling of lease break requests and acknowledgments. During file write or truncate operations, the server fails to properly validate and apply lease state transitions, resulting in service disruption for connected clients.	Story Points:	---
Clone Of:		Environment:
Last Closed:		Type:	---
Regression:	---	Mount Type:	---
Documentation:	---	CRM:
Verified Versions:		Category:	---
oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---	Target Upstream Version:
Embargoed:

Description OSIDB Bzimport 2026-10-23 12:24:32 UTC

In the Linux kernel, the following vulnerability has been resolved:

ksmbd: fix lease break and ack state handling

Do not skip valid lease states containing WRITE_CACHING when breaking
level-II/read leases for writes and truncates.

Handle lease break acknowledgments according to the SMB2 rule that the
acknowledged state must be a subset of the server's break target. Apply
the acknowledged state directly and keep the break pending on failed ACKs.