A side channel vulnerability on some of the AMD CPUs may allow an attacker to influence the return address prediction. This may result in speculative execution at an attacker-controlled address, potentially leading to information disclosure.
https://www.debian.org/security/2023/dsa-5475
https://www.amd.com/en/corporate/product-security/bulletin/AMD-SB-7005
https://lists.debian.org/debian-lts-announce/2023/08/msg00013.html