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

Impact

MULTI-TENANT ISOLATION: The vGPU plugin lets a guest VM allocate resources it is not authorised to hold, breaking the resource partition between tenants and reaching information disclosure and data tampering. 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. This is a direct authorisation failure on the guest/host boundary, not a memory-safety accident - the guest simply asks for something it should not get and the plugin agrees.

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 5383. 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