CVE-2009-4031

What it is

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.

At a glance

Exploitability

Can be exploited over the network without logging in. High risk of service disruption.

Exploit odds

3.1% chance of exploitation in the next 30 days (EPSS).

Fix

A patch, advisory or fixed version is referenced. Upgrade or apply it.

Timeline

1. 2009-11-29 13:07 UTC PublishedDisclosed publicly on CVE.org and NVD
2. 2026-06-16 23:12 UTC Last updatedMost recent change to the record

Why it ranks here

• Exploited in the wild: no, CISA does not list it.
• Exploit odds: 3.1% in the next 30 days (EPSS).
• Severity: 7.8 HIGH (CVSS).
• Fix: a patch or advisory is linked.

Details

Published

2009-11-29 13:07 UTC

Last modified

2026-06-16 23:12 UTC

Exploit probability

3.1% · EPSS, next 30 days

Weakness

CWE-20 · Improper input validation

Record status

Modified

Affected

• Linux Kernel < 2.6.32
• Linux Kernel 2.6.32

Attack profile CVSS 2.0 · 7.8

Attack vector

Network

Complexity

Low

Authentication

None

Confidentiality

None

Integrity

None

Availability

Complete

Is it in your code?

Hand this to your coding agent. It searches your project for the affected products and checks versions. Nothing leaves your machine.

Read https://cve-list.com/agent/cve/CVE-2009-4031.md and follow it. Check whether this project is affected by CVE-2009-4031. Read only. Don't change anything and don't upload my code. Tell me yes, no or not sure, with the file as proof.

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