--- title: "CVE-2009-4031\n | Ubuntu" description: Ubuntu is an open source software operating system that runs from the desktop, to the cloud, to all your internet connected things. url: https://ubuntu.com/security/CVE-2009-4031?format=md keywords: index, follow --- # CVE-2009-4031 Publication date 29 November 2009 Last updated 4 July 2026 --- Ubuntu priority **Medium** [Why this priority?](https://ubuntu.com/security/cves/about#priority ) Toggle side navigation ## 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. ### From the Ubuntu Security Team It was discovered that KVM did not correctly decode certain guest instructions. A local attacker in a guest could exploit this to trigger high scheduling latency in the host, leading to a denial of service. ## Status Show unmaintained releases | Package | Ubuntu Release | Status | | --- | --- | --- | | kvm | 11.04 natty | Not in release | | 10.10 maverick | Not in release | | 10.04 LTS lucid | Not in release | | 9.10 karmic | Not in release | | 9.04 jaunty | Ignored end of life | | 8.10 intrepid | Ignored end of life, was needs-triage | | 8.04 LTS hardy | Ignored end of life | | 6.06 LTS dapper | Not in release | | linux | 11.04 natty | Not affected | | 10.10 maverick | Not affected | | 10.04 LTS lucid | Not affected | | 9.10 karmic | Fixed 2.6.31-19.56 | | 9.04 jaunty | Fixed 2.6.28-18.59 | | 8.10 intrepid | Fixed 2.6.27-17.45 | | 8.04 LTS hardy | Fixed 2.6.24-27.65 | | 6.06 LTS dapper | Not in release | | linux-ec2 | 11.04 natty | Not in release | | 10.10 maverick | Ignored end of life | | 10.04 LTS lucid | Not affected | | 9.10 karmic | Fixed 2.6.31-19.56 | | 9.04 jaunty | Not in release | | 8.10 intrepid | Not in release | | 8.04 LTS hardy | Not in release | | 6.06 LTS dapper | Not in release | | linux-fsl-imx51 | 11.04 natty | Not in release | | 10.10 maverick | Not in release | | 10.04 LTS lucid | Not affected | | 9.10 karmic | Fixed 2.6.31-108.21 | | 8.04 LTS hardy | Not in release | | 6.06 LTS dapper | Not in release | | linux-lts-backport-maverick | 11.04 natty | Not in release | | 10.10 maverick | Not in release | | 10.04 LTS lucid | Not affected | | 9.10 karmic | Not in release | | 9.04 jaunty | Not in release | | 8.10 intrepid | Not in release | | 8.04 LTS hardy | Not in release | | 6.06 LTS dapper | Not in release | | linux-mvl-dove | 11.04 natty | Not in release | | 10.10 maverick | Not affected | | 10.04 LTS lucid | Not affected | | 9.10 karmic | Fixed 2.6.31-211.22 | | 8.04 LTS hardy | Not in release | | 6.06 LTS dapper | Not in release | | linux-source-2.6.15 | 11.04 natty | Not in release | | 10.10 maverick | Not in release | | 10.04 LTS lucid | Not in release | | 9.10 karmic | Not in release | | 9.04 jaunty | Not in release | | 8.10 intrepid | Not in release | | 8.04 LTS hardy | Not in release | | 6.06 LTS dapper | Not affected | | linux-ti-omap4 | 11.04 natty | Not affected | | 10.10 maverick | Not affected | | 10.04 LTS lucid | Not in release | | 9.10 karmic | Not in release | | 8.04 LTS hardy | Not in release | | 6.06 LTS dapper | Not in release | | qemu-kvm | 11.04 natty | Not affected | | 10.10 maverick | Not affected | | 10.04 LTS lucid | Not affected | | 9.10 karmic | Not affected | | 9.04 jaunty | Not in release | | 8.10 intrepid | Not in release | | 8.04 LTS hardy | Not in release | | 6.06 LTS dapper | Not in release | --- * [How can I get the fixes?](https://ubuntu.com/security/cves/about#security) * [What do statuses mean?](https://ubuntu.com/security/cves/about#statuses) * [Patch details](https://ubuntu.com/security/CVE-2009-4031?format=md#patch-details) ### Patch details For informational purposes only. We recommend not to cherry-pick updates. [How can I get the fixes?](https://ubuntu.com/security/cves/about#security) | Package | Patch details | | --- | --- | | linux | * Introduced by [1da177e](https://git.kernel.org/linus/1da177e4c3f41524e886b7f1b8a0c1fc7321cac2), fixed by [eb3c79e](https://git.kernel.org/linus/eb3c79e64a70fb8f7473e30fa07e89c1ecc2c9bb) | ## References * [MITRE](https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2009-4031) * [NVD](https://nvd.nist.gov/vuln/detail/CVE-2009-4031) * [Launchpad](https://launchpad.net/bugs/cve/CVE-2009-4031) * [Debian](https://security-tracker.debian.org/tracker/CVE-2009-4031) ### Related Ubuntu Security Notices (USN) + [USN-894-1](https://usn.ubuntu.com/USN-894-1) + Linux kernel vulnerabilities + 5 February 2010 ### Other references *