Bug 2532361 (CVE-2026-80959)

Summary:	CVE-2026-80959 kernel: dm-pcache: bound the persisted tail-position offset
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 device-mapper persistent cache (dm-pcache) component. A local attacker with administrative privileges (CAP_SYS_ADMIN) could provide a specially crafted cache device, leading to an out-of-bounds read. This vulnerability allows reading past the intended segment data, which may result in information disclosure or system instability.	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 2026-09-11 22:32:47 UTC

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

dm-pcache: bound the persisted tail-position offset

cache_pos_decode() takes the persisted key_tail and dirty_tail seg_off from
the cache device and addresses within the segment with it. A seg_off at or
past the segment data_size, controllable by whoever supplies the device
(CAP_SYS_ADMIN), reads past the segment data.

Reject a decoded seg_off that is not below the segment data_size.

Comment 1 Keith Grant 2026-09-14 16:35:31 UTC

Upstream advisory:
https://git.kernel.org/pub/scm/linux/security/vulns.git/plain/cve/published/2026/CVE-2026-80959.mbox