Xen
CVE-2021-28692
HIGH
Severity by source
AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H
Primary rating from NVD · only source for this CVE.
CVSS VectorNVD
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H
Lifecycle Timeline
1DescriptionNVD
inappropriate x86 IOMMU timeout detection / handling IOMMUs process commands issued to them in parallel with the operation of the CPU(s) issuing such commands. In the current implementation in Xen, asynchronous notification of the completion of such commands is not used. Instead, the issuing CPU spin-waits for the completion of the most recently issued command(s). Some of these waiting loops try to apply a timeout to fail overly-slow commands. The course of action upon a perceived timeout actually being detected is inappropriate: - on Intel hardware guests which did not originally cause the timeout may be marked as crashed, - on AMD hardware higher layer callers would not be notified of the issue, making them continue as if the IOMMU operation succeeded.
AnalysisAI
inappropriate x86 IOMMU timeout detection / handling IOMMUs process commands issued to them in parallel with the operation of the CPU(s) issuing such commands. Rated high severity (CVSS 7.1), this vulnerability is 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. inappropriate x86 IOMMU timeout detection / handling IOMMUs process commands issued to them in parallel with the operation of the CPU(s) issuing such commands. In the current implementation in Xen, asynchronous notification of the completion of such commands is not used. Instead, the issuing CPU spin-waits for the completion of the most recently issued command(s). Some of these waiting loops try to apply a timeout to fail overly-slow commands. The course of action upon a perceived timeout actually being detected is inappropriate: - on Intel hardware guests which did not originally cause the timeout may be marked as crashed, - on AMD hardware higher layer callers would not be notified of the issue, making them continue as if the IOMMU operation succeeded. Affected products include: Xen.
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 Privilege Escalation
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External POC / Exploit Code
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