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CVE-2021-28696: IOMMU page mapping issues on x86 T[his CNA information record relates to multiple CVEs; the text explains w...

IOMMU page mapping issues on x86 T[his CNA information record relates to multiple CVEs; the text explains which aspects/vulnerabilities correspond to which CVE.] Both AMD and Intel allow ACPI tables to specify regions of memory which should be left untranslated, which typically means these addresses should pass the translation phase unaltered. While these are typically device specific ACPI properties, they can also be specified to apply to a range of devices, or even all devices. On all systems with such regions Xen failed to prevent guests from undoing/replacing such mappings (CVE-2021-28694). On AMD systems, where a discontinuous range is specified by firmware, the supposedly-excluded middle range will also be identity-mapped (CVE-2021-28695). Further, on AMD systems, upon de-assigment of a physical device from a guest, the identity mappings would be left in place, allowing a guest continued access to ranges of memory which it shouldn't have access to anymore (CVE-2021-28696).

UnknownCVSS not scoredNot KEV-listedUpdated
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Glexia's TakeAutomated analysis

Security readout for executives and security teams

CVE-2021-28696 is a Xen hypervisor isolation flaw on AMD x86 systems. After a physical device is removed from a guest, Xen may leave certain identity memory mappings in place, so the guest could continue accessing memory ranges it should no longer reach. Exposure is most likely in Xen deployments using affected Xen 4.11.x through 4.15.x or xen-unstable on AMD x86 hardware where physical devices are assigned to guests and later de-assigned. Treat this as a high-priority virtualization isolation issue for Xen environments using AMD hosts and device passthrough. Patch affected hypervisors promptly, especially in multi-tenant or untrusted guest environments. Mitigation focus: Review Xen XSA-378 and applicable distribution advisories.; Upgrade Xen packages using vendor-provided fixes from Xen, Debian, Fedora, or Gentoo.; Prioritize hosts using PCI passthrough or device assignment to untrusted guests..

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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

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Vulnerability profileCVE Program record
Severity
Unknown
CVSS
Not scored
Known Exploited
No
Published
Official CVE source material

CNA and ADP enrichment extracted from CVE v5

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0CVSS vectors
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7Source links

CVSS and timeline data

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Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
Xenxen4.11.xListed
Xenxenxen-unstableListed
Xenxen4.12.xListed
Xenxen4.14.xListed
Xenxen4.15.xListed
Xenxen4.13.xListed
Weakness

CWE details

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