CVE-2013-4551
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 · uneditedXen 4.2.x and 4.3.x, when nested virtualization is disabled, does not properly check the emulation paths for (1) VMLAUNCH and (2) VMRESUME, which allows local HVM guest users to cause a denial of service (host crash) via unspecified vectors related to "guest VMX instruction execution."
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 confidenceThis is a denial of service vulnerability in Xen hypervisor versions 4.2.x and 4.3.x. When nested virtualization is disabled, the hypervisor does not properly validate the emulation paths for VMLAUNCH and VMRESUME instructions, which are VMX instructions used to enter VMX non-root mode. A malicious local HVM guest can exploit this improper validation to trigger a host crash.
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= 4.2.0= 4.2.1= 4.2.2= 4.2.3= 4.3.0= 4.3.1CVSS 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
- Adjacent
- Complexity
- M
- Authentication
- None
- Confidentiality
- None
- Integrity
- None
- Availability
- Complete
AV:A/AC:M/Au:N/C:N/I:N/A:C
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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Identify Xen hypervisor versionRun `xl version` or `xm version` to display the installed Xen hypervisor version number. Alternatively, check the package manager output (e.g., `rpm -q xen` or `dpkg -l xen-*`).Affected if The version displayed is 4.2.0, 4.2.1, 4.2.2, 4.2.3, 4.3.0, or 4.3.1.
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Confirm HVM guests are in useRun `xl list` or `xm list` to list all virtual machines. Inspect the output for VMs with type 'hvm' in the 'OS' or 'VM type' column. Alternatively, examine VM configuration files in /etc/xen/ for `builder = "hvm"` directives.Affected if Any HVM (Hardware Virtual Machine) guests are configured or running on the host.
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Verify nested virtualization statusCheck the nested virtualization setting by examining the Xen command line in /boot/grub/grub.cfg or by running `xl dmesg | grep -i nested`. Also inspect VM config files for `nestedhvm` or `nested` settings.Affected if Nested virtualization is explicitly disabled (nestedhvm = 0 or the feature is not enabled) or the hypervisor was built with nested virtualization support disabled.
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Confirm VMX instruction path exposureReview Xen hypervisor boot logs with `xl dmesg` or check /var/log/xen/boot.log for VMX-related entries. Verify that VMX (Intel Virtualization Technology) is available on the host CPU but nested virtualization is not actively in use by any guest.Affected if The host CPU supports VMX, nested virtualization is disabled or not configured, and HVM guests are running or can be created.
A system is affected if it runs Xen version 4.2.0 through 4.2.3 or 4.3.0 through 4.3.1, has HVM guests configured, and has nested virtualization disabled while VMX-capable CPUs are present.
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 Xen to a patched version (4.2.4+ or 4.3.2+). If immediate patching is not feasible, ensure only trusted VMs are run as HVM guests, though this does not fully mitigate the risk.
- Consultation4.0 h
- Implementation6.0 h
- Testing4.0 h
- Review / QA2.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2013-4551 — 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-2013-4551 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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- Verified mitigations, workarounds, and config changes
- Version or environment caveats, and links to real fixes
- No weaponised exploit code, or anything meant to cause harm
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