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XenOperating system

CVE-2023-34326

HIGH · 7.8 CVSS v3.1 Published 2024-01-05
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
80/100
Remediation priority · High
Zero-click

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 · unedited
The caching invalidation guidelines from the AMD-Vi specification (48882—Rev 3.07-PUB—Oct 2022) is incorrect on some hardware, as devices will malfunction (see stale DMA mappings) if some fields of the DTE are updated but the IOMMU TLB is not flushed. Such stale DMA mappings can point to memory ranges not owned by the guest, thus allowing access to unindented memory regions.

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 · moderate confidence

AMD-Vi IOMMU vulnerability where incorrect caching invalidation guidelines cause stale DMA mappings to persist after Device Table Entry (DTE) updates. When the IOMMU TLB is not flushed following DTE field modifications, stale translations can point to memory ranges outside the guest's assigned region, enabling unauthorized memory access.

MitigationRequires BIOS/firmware updates from AMD for affected hardware to correct the IOMMU TLB flush behavior; hypervisors may implement workarounds to force additional flushes where hardware-level fixes are unavailable.

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
XenOperating system
Affected:all versions

CVSS 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 checks

Work through these to decide whether this CVE applies to you.

  1. Confirm AMD hardware with AMD-Vi IOMMU is in use
    Check CPU vendor and IOMMU capability: look for 'AMD-Vi' or 'IOMMU' in boot logs (dmesg | grep -i iommu), or check /sys/kernel/debug/amd_vi or xl dmesg output for AMD IOMMU messages
    Affected if Running on AMD processor with AMD-Vi IOMMU hardware and Xen hypervisor is present
  2. Verify Xen hypervisor is running
    Run 'xl list' or 'xm list' to confirm Xen hypervisor is active; check 'xl dmesg' or /var/log/xen/ for Xen boot messages
    Affected if Xen hypervisor is running on AMD hardware with AMD-Vi IOMMU enabled
  3. Confirm IOMMU is enabled in Xen
    Check Xen configuration: look for 'iommu=1' or 'amd_iommu=on' in /boot/grub/grub.conf or /etc/default/grub, or run 'xl dmesg | grep -i iommu' to see if IOMMU initialized successfully
    Affected if IOMMU is enabled (iommu=1, amd_iommu=on, or similar) in Xen boot parameters
  4. Check for affected AMD processor families
    Identify the specific AMD processor model: run 'xl dmesg | grep -i cpu' or check 'cat /proc/cpuinfo' for the CPU model name. Known affected families include older AMD processors with AMD-Vi; compare against AMD advisory for specific family/model numbers
    Affected if Running on an AMD processor model that has the AMD-Vi IOMMU TLB flush issue (specific family/models per AMD advisory)
  5. Inspect IOMMU translation table activity
    Review system logs (dmesg, xl dmesg, /var/log/xen/) for any IOMMU translation errors, DMA mapping warnings, or unexpected memory access events that may indicate stale translation usage
    Affected if IOMMU-related errors or warnings appear in logs indicating translation or mapping issues

A system is affected if it runs Xen on AMD hardware with AMD-Vi IOMMU enabled, on a processor model impacted by the AMD-Vi TLB flush vulnerability.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

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 data
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Requires BIOS/firmware updates from AMD for affected hardware to correct the IOMMU TLB flush behavior; hypervisors may implement workarounds to force additional flushes where hardware-level fixes are unavailable.

Fix this in Xen Scoped from the published advisory
  • Consultation8.0 h
  • Implementation24.0 h
  • Testing16.0 h
  • Review / QA8.0 h
56.0 hours of engineering $9,760
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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2023-34326 in production — separate from our analysis above.

No notes yet

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What this is

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What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
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