CVE-2026-64285 KVM: SEV: Pin source page for write when adding CPUID data for SNP guest
A missing write pin in KVM SEV SNP guest setup allows kernel writes to read-only memory, potentially causing memory corruption or privilege escalation.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-64285?
CVE-2026-64285 is a medium-severity memory corruption vulnerability in Linux kernel, published on 25 Jul 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Official description
In the Linux kernel, the following vulnerability has been resolved:
KVM: SEV: Pin source page for write when adding CPUID data for SNP guest
When populating a guest_memfd instance with the initial CPUID data for an SNP guest, acquire a writable pin on the source page as KVM will write back the "correct" CPUID information if the userspace provided data is rejected by trusted firmware. Because KVM writes to the source page using a kernel mapping, pinning for read could result in KVM clobbering read-only memory.
Note, well-behaved VMMs are unlikely to be affected, as CPUID information is almost always dynamically generated by userspace, i.e. it's unlikely for the CPUID information to be backed by a read-only mapping.
[sean: rewrite shortlog and changelog, tag for stable@]
Which versions are affected by CVE-2026-64285?
It affects 1 product.
Products include Linux kernel.
How do I fix CVE-2026-64285?
Apply the vendor's patch.
Upgrade to the fixed version. Memory-safe languages, compiler hardening and fuzzing prevent most new cases. More about Memory corruption.
Is CVE-2026-64285 being exploited?
There is no known exploitation of CVE-2026-64285 in the wild and no public exploit code.
Other vulnerabilities in Linux kernel
Sources
Also known as DEBIAN-CVE-2026-64285, GHSA-9frv-wmxv-xpwj, ROOT-OS-UBUNTU-2204-CVE-2026-64285, UBUNTU-CVE-2026-64285.