AMD SEV-ES / SEV-SNP - transient-execution-amplified power side channel: MULTI-TENANT ISOLATION: Graz researchers

Impact

MULTI-TENANT ISOLATION: Graz researchers amplified the power side channel with transient execution to extract AES key bytes from inside SEV-ES and SEV-SNP guests. The significance for an operator is the trend line: power telemetry keeps turning out to be a channel that memory encryption does not cover, and each iteration extracts more with less. If you sell confidential computing, the host's power meter is part of your attack surface.

Who can reach it

Requires a malicious hypervisor with access to power telemetry (RAPL) on a host running confidential guests.

What to do

**No CVE and no microcode fix** - AMD's answer is to restrict or disable hypervisor RAPL access. That is a configuration change you can make today at no performance cost: ensure the host's energy interfaces are root-only and are not exposed to any process a tenant can influence, and do not pass power telemetry into guests. No reboot, no firmware. Combine with performance-determinism mode if you are also mitigating Collide+Power, accepting the throughput cost that carries.

References