Linux KernelOperating system · Linux
CVE-2009-4004
Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.
NVD · uneditedBuffer overflow in the kvm_vcpu_ioctl_x86_setup_mce function in arch/x86/kvm/x86.c in the KVM subsystem in the Linux kernel before 2.6.32-rc7 allows local users to cause a denial of service (memory corruption) or possibly gain privileges via a KVM_X86_SETUP_MCE IOCTL request that specifies a large number of Machine Check Exception (MCE) banks.
Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.
dbcve analysis · high confidenceBuffer overflow in the KVM subsystem's kvm_vcpu_ioctl_x86_setup_mce function in Linux kernel versions before 2.6.32-rc7 allows local users to trigger memory corruption via a KVM_X86_SETUP_MCE IOCTL request with an excessive number of MCE banks, potentially leading to denial of service or privilege escalation.
Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.
Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.
NVD · CPE data
Linux KernelOperating system
<= 2.6.31.14= 2.6.32CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.
From the vector- Attack vector
- Local
- Complexity
- Low
- Privileges
- Low
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- High
- Integrity
- High
- Availability
- High
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.
dbcve checksWork through these to decide whether this CVE applies to you.
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Check kernel versionRun 'uname -r' to get the running kernel version and compare it against the affected ranges: any version <= 2.6.31.14 or exactly 2.6.32Affected if The kernel version is 2.6.31.14 or earlier, or exactly 2.6.32
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Verify KVM is presentCheck for KVM kernel modules by running 'lsmod | grep kvm' or checking /dev/kvm exists with 'ls -l /dev/kvm'Affected if KVM modules are loaded or /dev/kvm exists, indicating the KVM subsystem is available
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Confirm MCE support is enabledCheck if Machine Check Exception support is available by examining /proc/cpuinfo for 'mce' flags or running 'mcelog --version' to see if MCE logging tools are installedAffected if MCE support is present in the kernel and users can access MCE configuration
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Check for IOCTL accessVerify that the KVM device node is accessible for IOCTL operations by checking permissions on /dev/kvm with 'ls -l /dev/kvm'Affected if The user has read/write access to /dev/kvm, enabling them to issue KVM_X86_SETUP_MCE IOCTL requests
A system is affected if it runs a vulnerable kernel version (<=2.6.31.14 or =2.6.32) and has KVM with MCE support enabled, allowing a local user to trigger the buffer overflow via KVM_X86_SETUP_MCE IOCTL with excessive MCE banks
Generated from the published advisory. Verify against your own configuration.
Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.
From vendor dataUpgrade Linux kernel to version 2.6.32-rc7 or later to obtain the patch that adds proper bounds checking on the MCE bank count parameter.
Fix this in Linux Kernel
Scoped from the published advisory
- Consultation2.0 h
- Implementation3.0 h
- Testing3.0 h
- Review / QA2.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $2,800.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2009-4004 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2009-4004 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
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- Version or environment caveats, and links to real fixes
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