Improper input validation in the SMM handler may allow a privileged attacker to overwrite SMRAM, potentially leading to arbitrary code execution.
https://www.amd.com/en/resources/product-security/bulletin/amd-sb-5004.html
https://www.amd.com/en/resources/product-security/bulletin/amd-sb-4008.html
https://www.amd.com/en/resources/product-security/bulletin/amd-sb-3009.html