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CVE-2023-46835: x86/AMD: mismatch in IOMMU quarantine page table levels

The current setup of the quarantine page tables assumes that the quarantine domain (dom_io) has been initialized with an address width of DEFAULT_DOMAIN_ADDRESS_WIDTH (48) and hence 4 page table levels. However dom_io being a PV domain gets the AMD-Vi IOMMU page tables levels based on the maximum (hot pluggable) RAM address, and hence on systems with no RAM above the 512GB mark only 3 page-table levels are configured in the IOMMU. On systems without RAM above the 512GB boundary amd_iommu_quarantine_init() will setup page tables for the scratch page with 4 levels, while the IOMMU will be configured to use 3 levels only, resulting in the last page table directory (PDE) effectively becoming a page table entry (PTE), and hence a device in quarantine mode gaining write access to the page destined to be a PDE. Due to this page table level mismatch, the sink page the device gets read/write access to is no longer cleared between device assignment, possibly leading to data leaks.

MediumCVSS 5.5Not KEV-listedUpdated
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Glexia's TakeAutomated analysis

Security readout for executives and security teams

CVE-2023-46835 is a Xen AMD IOMMU issue that can let a quarantined device retain access to memory contents that should have been cleared between device assignments. The main business risk is confidential data exposure on affected virtualization hosts, not service outage or confirmed remote takeover. Exposure is most likely on Xen hosts using AMD-Vi IOMMU and device assignment/quarantine on systems with no RAM above the 512GB boundary. Exact affected versions are not listed in the provided bundle; Xen XSA-445 should be treated as authoritative. Treat as a targeted confidentiality risk for Xen virtualization infrastructure. Prioritize remediation where device passthrough or reassignment is used on AMD hosts, especially multi-tenant or sensitive workloads. It is not presented as actively exploited in the supplied evidence. Mitigation focus: Review Xen XSA-445 for affected versions and vendor-supported fixes.; Apply Xen or distribution security updates that address XSA-445.; Prioritize hosts using AMD-Vi IOMMU with device assignment workflows..

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Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.

Potential ATT&CK relevance

Conservative CVE-to-ATT&CK context

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CVE-2023-46835 mapping review

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Vulnerability profileCVE Program record
Severity
Medium
CVSS
5.5 (3.1)
Known Exploited
No
Published

Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N

Official CVE source material

CNA and ADP enrichment extracted from CVE v5

These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.

1CVSS vectors
0Timeline events
0ADP providers
2Source links

CVSS vector scores

1 official score

We collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.

ScoreVersionSeverityVectorExploitImpactSource
5.5CVSS 3.1MediumCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N1.83.6Primary CVE score

Vulnerability scoring details

Base CVSS 3.1 score

5.5Medium
CVSS 3.1 vector shape for CVE-2023-46835Attack VectorAttack ComplexityPrivileges RequiredUser InteractionScopeConfidentiality ImpactIntegrity ImpactAvailability Impact

Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N

Attack Vector
NetworkAdjacentLocalPhysical
Attack Complexity
LowHigh
Privileges Required
NoneLowHigh
User Interaction
NoneRequired
Scope
ChangedUnchanged
Confidentiality Impact
HighLowNone
Integrity Impact
HighLowNone
Availability Impact
HighLowNone

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
XenXenconsult Xen advisory XSA-445unknown
Weakness

CWE details

CWE-787

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CWE-787 · source CWE mapping

Out-of-bounds Write

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