CVE-2026-64309 crypto: ccp - Do not initialize SNP for ioctl(SNP_COMMIT)

Medium 5.5 Published 25 Jul 2026 Updated 17 Aug 2026

A local attacker can crash the host system by triggering a specific ioctl on the CCP driver when SEV initialization fails, affecting Linux kernel users.

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-2026-64309?

CVE-2026-64309 is a medium-severity denial of service 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:

crypto: ccp - Do not initialize SNP for ioctl(SNP_COMMIT)

Sashiko notes:

> if SEV initialization fails and KVM is actively running normal VMs, could a > userspace process trigger this code path via /dev/sev ioctls (e.g., > SEV_PDH_GEN) and zero out MSR_VM_HSAVE_PA globally? Would the next VMRUN > execution for an active VM trigger a general protection fault and crash the > host?

The SNP_COMMIT command does not require the firmware to be in any particular state. Skip initializing it if it was previously uninitialized.

The SEV-SNP firmware specification doc 56860 does not mention SNP_COMMIT in Table 5 as a command that is allowed in the UNINIT state, but it is in fact allowed and a future documentation update will reflect that.

Weakness: CWE-908

Which versions are affected by CVE-2026-64309?

It affects 1 product.

Products include Linux kernel.

How do I fix CVE-2026-64309?

Apply the vendor's patch.

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-2026-64309 being exploited?

There is no known exploitation of CVE-2026-64309 in the wild and no public exploit code.

All Linux kernel vulnerabilities

Sources

Also known as BELL-CVE-2026-64309, DEBIAN-CVE-2026-64309, GHSA-8w5v-46pm-6rg4, ROOT-OS-UBUNTU-2204-CVE-2026-64309, UBUNTU-CVE-2026-64309.