Tom Dohrmann

**Name of the Vulnerable Software and Affected Versions** SEV firmware (affected versions not specified) **Description** A code bug in Secure TSC may allow an attacker with high privileges to cause a guest to observe an incorrect TSC when Secure TSC is enabled, potentially resulting in a loss of guest integrity. **Recommendations** At the moment, there is no information about a newer version that contains a fix for this vulnerability.

**Name of the Vulnerable Software and Affected Versions** AMD SEV-SNP (affected versions not specified) **Description** A privileged attacker can prevent delivery of debug exceptions to SEV-SNP guests, potentially resulting in guests not receiving expected debug information. The issue is related to the implementation of the SEV-SNP (Secure Nested Paging) protective mechanism for virtual machines running on servers with AMD processors, and is associated with incorrect clearance or release of resources. **Recommendations** At the moment, there is no information about a newer version that contains a fix for this vulnerability.

**Name of the Vulnerable Software and Affected Versions** SEV Firmware (affected versions not specified) **Description** The issue is related to the failure to initialize memory in SEV Firmware, which may allow a privileged attacker to access stale data from other guests. **Recommendations** At the moment, there is no information about a newer version that contains a fix for this vulnerability.

**Name of the Vulnerable Software and Affected Versions** Linux kernel versions prior to 6.5.9 **Description** The issue is caused by errors in synchronization when using a shared resource, potentially allowing an attacker to execute arbitrary code. It involves incorrect access checking in the #VC handler and instruction emulation of the SEV-ES emulation of MMIO accesses, which could lead to arbitrary write access to kernel memory and thus privilege escalation. This depends on a race condition through which userspace can replace an instruction before the #VC handler reads it. **Recommendations** For Linux kernel versions prior to 6.5.9, update to version 6.5.9 or later to resolve the issue. As a temporary workaround, consider restricting access to MMIO registers to minimize the risk of exploitation. Avoid using the #VC handler and SEV-ES emulation of MMIO accesses in sensitive operations until the issue is resolved.