Xen
CVE-2021-28702
HIGH
Severity by source
AV:P/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H
Primary rating from NVD · only source for this CVE.
CVSS VectorNVD
CVSS:3.1/AV:P/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H
Lifecycle Timeline
1DescriptionNVD
PCI devices with RMRRs not deassigned correctly Certain PCI devices in a system might be assigned Reserved Memory Regions (specified via Reserved Memory Region Reporting, "RMRR"). These are typically used for platform tasks such as legacy USB emulation. If such a device is passed through to a guest, then on guest shutdown the device is not properly deassigned. The IOMMU configuration for these devices which are not properly deassigned ends up pointing to a freed data structure, including the IO Pagetables. Subsequent DMA or interrupts from the device will have unpredictable behaviour, ranging from IOMMU faults to memory corruption.
AnalysisAI
PCI devices with RMRRs not deassigned correctly Certain PCI devices in a system might be assigned Reserved Memory Regions (specified via Reserved Memory Region Reporting, "RMRR"). Rated high severity (CVSS 7.6), this vulnerability is no authentication required, low attack complexity. No vendor patch available.
Technical ContextAI
This vulnerability is classified as Improper Privilege Management (CWE-269), which allows attackers to escalate privileges to gain unauthorized elevated access. PCI devices with RMRRs not deassigned correctly Certain PCI devices in a system might be assigned Reserved Memory Regions (specified via Reserved Memory Region Reporting, "RMRR"). These are typically used for platform tasks such as legacy USB emulation. If such a device is passed through to a guest, then on guest shutdown the device is not properly deassigned. The IOMMU configuration for these devices which are not properly deassigned ends up pointing to a freed data structure, including the IO Pagetables. Subsequent DMA or interrupts from the device will have unpredictable behaviour, ranging from IOMMU faults to memory corruption. Affected products include: Xen, Fedoraproject Fedora, Debian Debian Linux.
RemediationAI
No vendor patch is available at time of analysis. Monitor vendor advisories for updates. Apply principle of least privilege, validate privilege transitions, implement proper role separation.
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Same weakness CWE-269 – Improper Privilege Management
View allSame technique Buffer Overflow
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External POC / Exploit Code
Leaving vuln.today