CVE-2026-64307 crypto: ccp - Do not initialize SNP for ioctl(SNP_CONFIG)
A local attacker can crash the host system by triggering a specific ioctl path when SEV initialization fails, affecting Linux kernel users with AMD SEV enabled.
- 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-2026-64307?
CVE-2026-64307 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_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 has failed, continue to refuse to initialize until the ccp module is unloaded
Which versions are affected by CVE-2026-64307?
It affects 1 product.
Products include Linux kernel.
How do I fix CVE-2026-64307?
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-2026-64307 being exploited?
There is no known exploitation of CVE-2026-64307 in the wild and no public exploit code.
Other vulnerabilities in Linux kernel
Sources
Also known as BELL-CVE-2026-64307, DEBIAN-CVE-2026-64307, GHSA-wv9v-6465-83fw, ROOT-OS-UBUNTU-2204-CVE-2026-64307, UBUNTU-CVE-2026-64307.