AMD Flaw - Result of simple programming flaws, unclear security boundaries, and insufficient security testing.

• All exploits require the ability to run an executable as admin (no physical access is required)
• MASTERKEY additionally requires issuing a BIOS update + reboot

Potential technical impact

• Code execution in the PSP and SMM (no visibility to typical security products)
• Persistence across OS reinstallation and BIOS updates
• Block or infect further BIOS updates, or brick the device
• Bypass Windows Credential Guard
• Bypass Secure Encrypted Virtualization (SEV)
• Bypass Secure Boot
• Bypass or attack security features implemented on top of the PSP (e.g., fTPM)

https://blog.trailofbits.com/2018/03/15/amd-flaws-technical-summary/