Bug 2529852

Summary:	CVE-2026-79603 xen: Xen: PV guests can modify scrubbed memory pages due to stale TLB entries [fedora-all]
Product:	[Fedora] Fedora	Reporter:	Vladimir Vasilev <vvasilev>
Component:	xen	Assignee:	Michael Young <m.a.young>
Status:	CLOSED ERRATA	QA Contact:	Fedora Extras Quality Assurance <extras-qa>
Severity:	high	Docs Contact:
Priority:	high
Version:	rawhide	CC:	jforbes, m.a.young
Target Milestone:	---	Keywords:	Security, SecurityTracking
Target Release:	---
Hardware:	Unspecified
OS:	Unspecified
Whiteboard:	{"flaws": ["99a97718-04ae-48ca-8fc2-ccb9c7acb0f1"]}
Fixed In Version:	xen-4.21.2-2.fc44 xen-4.20.4-2.fc43	Doc Type:	---
Doc Text:		Story Points:	---
Clone Of:		Environment:
Last Closed:	2026-10-03 01:10:00 UTC	Type:	---
Regression:	---	Mount Type:	---
Documentation:	---	CRM:
Verified Versions:		Category:	---
oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---	Target Upstream Version:
Embargoed:
Bug Depends On:
Bug Blocks:	2529764

Description Vladimir Vasilev 2026-09-08 14:53:06 UTC

Disclaimer: Community trackers are created by Red Hat Product Security team on a best effort basis. Package maintainers are required to ascertain if the flaw indeed affects their package, before starting the update process.

x86 PV guests can free memory pages while still keeping a stale TLB entry
pointing to them.  A TLB flush is only issued by Xen (if needed) when the
page is re-used.  Since it's possible for the page to be scrubbed ahead of
the TLB flush, there's a window where a PV guest can modify an already
scrubbed page.

Comment 1 Fedora Update System 2026-09-16 21:28:50 UTC

FEDORA-2026-1d448c1d40 (xen-4.21.2-2.fc44) has been submitted as an update to Fedora 44.
https://bodhi.fedoraproject.org/updates/FEDORA-2026-1d448c1d40

Comment 2 Fedora Update System 2026-09-17 18:14:47 UTC

FEDORA-2026-1d448c1d40 has been pushed to the Fedora 44 testing repository.
Soon you'll be able to install the update with the following command:
`sudo dnf upgrade --enablerepo=updates-testing --refresh --advisory=FEDORA-2026-1d448c1d40`
You can provide feedback for this update here: https://bodhi.fedoraproject.org/updates/FEDORA-2026-1d448c1d40

See also https://fedoraproject.org/wiki/QA:Updates_Testing for more information on how to test updates.

Comment 3 Fedora Update System 2026-09-17 20:19:16 UTC

FEDORA-2026-a9ea805bc1 (xen-4.20.4-2.fc43) has been submitted as an update to Fedora 43.
https://bodhi.fedoraproject.org/updates/FEDORA-2026-a9ea805bc1

Comment 4 Fedora Update System 2026-09-18 01:34:53 UTC

FEDORA-2026-a9ea805bc1 has been pushed to the Fedora 43 testing repository.
Soon you'll be able to install the update with the following command:
`sudo dnf upgrade --enablerepo=updates-testing --refresh --advisory=FEDORA-2026-a9ea805bc1`
You can provide feedback for this update here: https://bodhi.fedoraproject.org/updates/FEDORA-2026-a9ea805bc1

See also https://fedoraproject.org/wiki/QA:Updates_Testing for more information on how to test updates.

Comment 5 Fedora Update System 2026-10-03 01:10:00 UTC

FEDORA-2026-1d448c1d40 (xen-4.21.2-2.fc44) has been pushed to the Fedora 44 stable repository.
If problem still persists, please make note of it in this bug report.

Comment 6 Fedora Update System 2026-10-03 01:34:04 UTC

FEDORA-2026-a9ea805bc1 (xen-4.20.4-2.fc43) has been pushed to the Fedora 43 stable repository.
If problem still persists, please make note of it in this bug report.