CVE-2026-64308 crypto: ccp - Do not initialize SNP for ioctl(SNP_VLEK_LOAD)
A flaw in the Linux kernel's CCP driver allows a local attacker to crash the host by triggering a specific ioctl when SEV initialization fails.
- 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-2026-64308?
CVE-2026-64308 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_VLEK_LOAD)
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 SEV firmware docs for SNP_VLEK_LOAD note:
> On SNP_SHUTDOWN, the VLEK is deleted.
That is, the initialization/shutdown wrapper here is pointless, because the firmware immediately throws away the key anyway. Instead, refuse to do anything if SNP has not been previously initialized.
This is an ABI break: before, this was a no-op and almost certainly a mistake by userspace, and now it returns -ENODEV. ABI compatibility could be maintained here by simply returning 0 in the check instead.
Which versions are affected by CVE-2026-64308?
It affects 1 product.
Products include Linux kernel.
How do I fix CVE-2026-64308?
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-2026-64308 being exploited?
There is no known exploitation of CVE-2026-64308 in the wild and no public exploit code.
Other vulnerabilities in Linux kernel
Sources
Also known as BELL-CVE-2026-64308, DEBIAN-CVE-2026-64308, GHSA-jg4q-h984-9pjc, ROOT-OS-UBUNTU-2204-CVE-2026-64308, UBUNTU-CVE-2026-64308.