NVIDIA vGPU software - Virtual GPU Manager (host-side vGPU plugin / nvidia.ko): MULTI-TENANT ISOLATION: The host vGPU

Impact

MULTI-TENANT ISOLATION: The host vGPU plugin lets a guest reach global GPU resources, producing information disclosure, data tampering and privilege escalation across the partition. The attacker sits inside a tenant guest VM and the blast radius is the hypervisor host, which is running every other tenant's vGPU on the same physical GPU. This is precisely the boundary a vGPU-based multi-tenant offering is sold on. 'Global resources' on a shared physical GPU means state belonging to other tenants - this is a cross-tenant read/write primitive, not just a host bug.

Who can reach it

A tenant inside their own guest VM, driving the paravirtualised vGPU control interface. Several of these need only an unprivileged process in the guest; the rest need guest root, which a tenant already has on a VM they rented. No host credentials are involved at any point.

What to do

Patch the vGPU Manager on the hypervisor host per bulletin 5586. Cost: the highest of any class here. The host driver cannot be reloaded while vGPUs are attached, so every tenant VM on that hypervisor must be live-migrated or powered off - a full host drain. NVIDIA also enforces a supported host/guest driver skew, so budget a matching guest-driver campaign in the same window or tenants lose their vGPU on next boot.

References