CVE-2011-1751
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 · uneditedThe pciej_write function in hw/acpi_piix4.c in the PIIX4 Power Management emulation in qemu-kvm does not check if a device is hotpluggable before unplugging the PCI-ISA bridge, which allows privileged guest users to cause a denial of service (guest crash) and possibly execute arbitrary code by sending a crafted value to the 0xae08 (PCI_EJ_BASE) I/O port, which leads to a use-after-free related to "active qemu timers."
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 confidenceThe pciej_write function in QEMU-KVM's PIIX4 Power Management emulation (hw/acpi_piix4.c) lacks validation to check if a device is hotpluggable before performing an unplug operation on the PCI-ISA bridge. A privileged guest user can write a crafted value to I/O port 0xae08 (PCI_EJ_BASE), triggering a use-after-free condition with active QEMU timers, potentially causing guest denial of service or arbitrary code execution.
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= 0.1.0= 0.1.1= 0.1.2= 0.1.3= 0.1.4= 0.1.5= 0.1.6= 0.2.0= 0.3.0= 0.4.0= 0.4.1= 0.4.2CVSS 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
- Single
- Confidentiality
- Complete
- Integrity
- Complete
- Availability
- Complete
AV:A/AC:M/Au:S/C:C/I:C/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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Check QEMU versionRun 'qemu --version' or 'qemu-kvm --version' on the host to obtain the installed QEMU version numberAffected if The installed version matches 0.1.0 through 0.4.2 (any of: 0.1.0, 0.1.1, 0.1.2, 0.1.3, 0.1.4, 0.1.5, 0.1.6, 0.2.0, 0.3.0, 0.4.0, 0.4.1, 0.4.2)
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Verify PIIX4 PM emulation is in useExamine the QEMU command line or VM XML configuration for the presence of the PIIX4 chipset with ACPI support (look for 'piix4' or 'PIIX4' in the device configuration)Affected if The virtual machine configuration includes PIIX4 Power Management emulation (hw/acpi_piix4.c)
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Confirm PCI_EJ_BASE port is accessibleCheck the QEMU command line arguments or VM XML for the presence of '-device pci-bridge' or similar PCI bridge device that maps I/O port 0xae08 (PCI_EJ_BASE)Affected if The VM has a PCI-ISA bridge device configured that exposes the PCI_EJ_BASE port at address 0xae08
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Identify if guest has privileged accessReview VM access controls and determine if untrusted or potentially malicious users have privileged access inside the guest OSAffected if Untrusted or non-administrative guest users have the ability to execute privileged operations that can write to I/O ports
The environment is affected if the QEMU version is 0.1.0 through 0.4.2 AND the VM uses PIIX4 Power Management emulation with PCI bridge devices accessible to privileged guest users.
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 dataApply the upstream patch to qemu-kvm that adds hotpluggability validation in pciej_write before allowing PCI bridge removal, or upgrade to a patched qemu-kvm version that addresses this vulnerability.
- Consultation2.0 h
- Implementation4.0 h
- Testing3.0 h
- Review / QA2.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2011-1751 — 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-2011-1751 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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