Recently discovered Downfall and Inception vulnerabilities in Intel and AMD processors are also affecting Mac computers built with Intel CPUs.
This vulnerabilities could lead to security keys leakage to unprivileged code. There are no known exploits using this vulnerability at the time of writing.
AMD and Intel have both already released OS-level microcode software updates to address both issues. Both companies have also said that they're not aware of any active in-the-wild exploits of either vulnerability. Consumer, workstation, and server CPUs are all affected, making patching particularly important for server administrators.Ars Technica