CVE-2026-42493 x86 shadow paging is deprecated
Xen deprecates x86 shadow paging due to excessive resource consumption risks, requiring users to switch to HAP or shim modes to avoid potential denial of service.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-42493?
CVE-2026-42493 is a high-severity denial of service vulnerability in Xen, published on 28 Jul 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
Addressing certain issues, in particular related to operations which may take excessively long and therefore would need preemption, has turned out overly costly. Since alternatives (HVM/PVH: HAP, PV: shim) are commonly available, the decision was to deprecate the functionality, while still retaining it for people to use at their own (security) risk. Memory-wise small enough guests may still be okay to run.
Weakness: CWE-400
Which versions are affected by CVE-2026-42493?
How do I fix CVE-2026-42493?
Change a configuration setting.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2026-42493 being exploited?
There is no known exploitation of CVE-2026-42493 in the wild and no public exploit code.
Sources
Also known as ALPINE-CVE-2026-42493, DEBIAN-CVE-2026-42493, GHSA-7jxp-562x-944j, UBUNTU-CVE-2026-42493.