CVE-2026-79603 Unconditionally do TLB flushing ahead of page scrubbing
A race condition in Xen allows PV guests to modify scrubbed memory pages, potentially leading to data corruption or privilege escalation.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-79603?
CVE-2026-79603 is a medium-severity vulnerability in Xen, published on 8 Sep 2026. Any signed-in user can exploit it over the network, with no action from the victim.
Official description
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.
Weakness: CWE-664
Which versions are affected by CVE-2026-79603?
How do I fix CVE-2026-79603?
Apply the vendor's patch.
Is CVE-2026-79603 being exploited?
There is no known exploitation of CVE-2026-79603 in the wild and no public exploit code.
Sources
Also known as ALPINE-CVE-2026-79603, DEBIAN-CVE-2026-79603, GHSA-pwv5-r8hr-fvgr, UBUNTU-CVE-2026-79603.