https://www.bleepingcomputer.com/news/security/new-amd-sinkclose-flaw-helps-install-nearly-undetectable-malware/

AMD is warning about a high-severity CPU vulnerability named SinkClose that impacts multiple generations of its EPYC, Ryzen, and Threadripper processors. The vulnerability allows attackers with Kernel-level (Ring 0) privileges to gain Ring -2 privileges and install malware that becomes nearly undetectable.

Ring -2 is one of the highest privilege levels on a computer, running above Ring -1 (used for hypervisors and CPU virtualization) and Ring 0, which is the privilege level used by an operating system's Kernel.