Linux KVM SEV API - host kernel crash from unprivileged guest creation: A non-root host user-level application can

Impact

A non-root host user-level application can crash the host kernel simply by creating a confidential guest through the KVM SEV API. Denial of service against the whole node from an unprivileged local process - on a GPU host that means every training job on the box dies because somebody with shell access called an ioctl.

Who can reach it

Local, **unprivileged** - the notable part. Only needs access to /dev/kvm, which on many hosts is more widely granted than people assume.

What to do

Fixed in the Linux kernel. Take the distro kernel update (RHEL/Rocky, Ubuntu, SLES) and reboot the host - no firmware, VBIOS or AGESA step. On a GPU fleet this is a cordon, drain and rolling reboot; plan it as normal kernel maintenance. Also audit who has /dev/kvm on your GPU hosts; if nothing on the node runs VMs, the device should not be world-accessible.

References