Xen Hypervisor TLB Flush Race Exposes PV Guest Memory Modification
CVE-2026-79603 Published on September 8, 2026
Unconditionally do TLB flushing ahead of page scrubbing
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.
Vulnerability Analysis
CVE-2026-79603 can be exploited with network access, and requires small amount of user privileges. This vulnerability is considered to have a low attack complexity. The potential impact of an exploit of this vulnerability is considered to have a small impact on confidentiality, a small impact on integrity and availability.
Weakness Type
Improper Control of a Resource Through its Lifetime
The software does not maintain or incorrectly maintains control over a resource throughout its lifetime of creation, use, and release.
Products Associated with CVE-2026-79603
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