Preface: AMD-SB-3042 is a formal advisory for a specific vulnerability, while AMD-SB-3043 is an advisory regarding an analytical tool (SNPeek) used to detect such vulnerabilities.
Background: If AMD zen5 operating AMD SEV-SNP, traditional hypervisor especially VMware or Hyper-V management include encryption will handle by hypervisor embedded in Xen5, so SNPeek collect the traffic is un-encrypted data. Details shown as below:
Limitations of SNPeek If using a tool like SNPeek to intercept traffic on the host side: It can only see data marked as “Shared” (usually for use by the hypervisor to assist with network or disk I/O). Data in Private Memory is always encrypted to SNPeek; the hypervisor cannot read its plaintext content at all. Potential Risk Warning Despite strong hardware encryption, the recently discovered StackWarp (CVE-2025-29943) vulnerability shows that a malicious hypervisor could still influence the execution path of Zen 5 virtual machines by manipulating the CPU’s internal “Stack Engine.” While this doesn’t mean it can directly “read” encrypted memory, it can achieve indirect attacks.
AMD-SB-3043: Analytical Framework (SNPeek)
- Nature: A bulletin regarding a research framework and toolkit for evaluating side-channel risks in Confidential VMs (CVM).
- Core Content: Describes the SNPeek open-source toolkit.
- Function & Purpose:
- SNPeek is not a single vulnerability but an automated analysis pipeline that uses machine learning to assess how sensitive a CVM application is to side-channel attacks.
- It helps developers quantify how much information an application might leak when running in encrypted environments like SEV-SNP.
- It provides configurable attack primitives to help developers locate “weak points” in their code and guides the implementation of mitigations (e.g., oblivious memory access).
Official details and announcement: AMD’s assessment is that all side-channel techniques demonstrated in the paper fall within the category of already known, documented, and out of scope behaviors according to the published SEV/SNP threat model. AMD has introduced features on Zen 5 processors—specifically Ciphertext Hiding and PMC Virtualization—that address the ciphertext visibility and HPC based leakage paths highlighted by the researchers.
AMD recommends software developers employ existing best practices, including constant-time algorithms, and avoiding secret-dependent data accesses where appropriate. Please refer to the link for details – https://www.amd.com/en/resources/product-security/bulletin/amd-sb-3043.html