Insufficient DRAM address validation in System Management Unit (SMU) may allow an attacker to read/write from/to an invalid DRAM address, potentially resulting in denial-of-service.
https://www.amd.com/en/corporate/product-security/bulletin/AMD-SB-5001
https://www.amd.com/en/corporate/product-security/bulletin/AMD-SB-4002
https://www.amd.com/en/corporate/product-security/bulletin/AMD-SB-3002