AMD Secure Processor - SoC security-configuration registers: MULTI-TENANT ISOLATION: A local attacker can make

Impact

MULTI-TENANT ISOLATION: A local attacker can make unauthorised changes to the SoC's security configuration registers and from there corrupt the AMD Secure Processor's encrypted memory. Corrupting ASP memory is not just a crash - it is a route to influencing what the secure processor computes, which is the same engine that gates memory encryption and attestation for every confidential guest on the node.

Who can reach it

Local, with access to the SoC register interface - root on the host.

What to do

Fixed in AMD reference firmware (AGESA / SEV firmware) and delivered to you only as an OEM SBIOS/BIOS package - Dell, HPE, Supermicro, Lenovo, Gigabyte and the ODMs each rebuild and requalify AMD's AGESA drop before it ships. **Expect months, not weeks**: AMD publishes the bulletin, the OEM ships BIOS somewhere between one and six months later, and for platforms past their support window it may never arrive at all. Applying it is a full node power cycle with the host drained - not a driver reload, not a live patch. Track it as a firmware campaign per server SKU, not per kernel version, and verify afterwards by reading back the SMU/PSP firmware version rather than trusting the BIOS revision string. Because this sits inside the SEV-SNP trust boundary, the update also moves the platform's reported TCB version: after patching you must refresh VCEK certificates from AMD's KDS and update whatever attestation policy your tenants (or your own confidential-VM control plane) pin against, or every guest launch will start failing validation.

References