CVE-2026-64307

Technical Description

In the Linux kernel, the following vulnerability has been resolved:

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

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?

Refuse to re-try initialization if SNP is not already initialized for

SNP_CONFIG.

This is technically an ABI break: before if SNP initialization failed it

could be transparently retriggered by this ioctl, and if no VMs were

running, everything worked fine. Hopefully this is enough of a corner case

that nobody will notice, but someone does, there are a few options:

* do something like symbol_get() for kvm and refuse to initialize if KVM is

loaded

* check each cpu's HSAVE_PA for non-zero data before re-initializing

* once initialization h

Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

References