What’s Vulnerable › Vulnerabilities

CVE-2009-4031

• Severity: high (CVSS 7.8 v2.0)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 3.1% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2009-11-29 · updated 2026-06-16
• Weakness: CWE-20

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.

Affected products

• Linux kernel: before 2.6.32; 2.6.32, 2.6.32-rc1, 2.6.32-rc2, 2.6.32-rc3, 2.6.32-rc4, 2.6.32-rc5 (+2) — fixed in 2.6.32

How to fix

Upgrade to a fixed version: Linux kernel 2.6.32. Check the vendor advisory for mitigations.

References

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

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