https://seclists.org/oss-sec/2026/q3/672: Xen Security Advisory 511 v3 (CVE-2026-79603) - Unconditionally do TLB flushing ahead of page scrubbing
Published Sep 8, 2026
·Updated
Affected Software
1 affected component
Xen Project Xen>=undefined
Frequently Asked Questions
1
Which deployments are exposed to cross-guest information exchange?
Deployments running Xen 4.13 or later with xsm=silo scrub-domheap configured are affected when x86 PV guests are present. The advisory states that this configuration does not prevent information exchange among guests in the presence of PV guests.
2
What must an attacker control to exploit this issue?
An attacker needs control of an x86 PV guest. The guest can free pages while retaining stale TLB entries and modify a page after it has been scrubbed but before the required TLB flush occurs.
3
Are Xen 4.12 and earlier affected?
No. Xen 4.12 and earlier do not have the scrub-domheap command-line option and are not vulnerable according to the advisory.
4
What can be done if the patch cannot be applied immediately?
The advisory lists no known mitigation. Applying the appropriate attached patch is the stated resolution.