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CVE-2021-28695

Published: 27 August 2021

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).

Notes

AuthorNote
mdeslaur
hypervisor packages are in universe. For
issues in the hypervisor, add appropriate
tags to each section, ex:
Tags_xen: universe-binary

Priority

Medium

Cvss 3 Severity Score

6.8

Score breakdown

Status

Package Release Status
xen
Launchpad, Ubuntu, Debian
hirsute Ignored
(end of life)
jammy Needs triage

trusty Does not exist

bionic Needs triage

focal Needs triage

xenial Needs triage

upstream Needs triage

kinetic Ignored
(end of life, was needs-triage)
impish Ignored
(end of life)
mantic Needs triage

lunar Ignored
(end of life, was needs-triage)
Binaries built from this source package are in Universe and so are supported by the community.

Severity score breakdown

Parameter Value
Base score 6.8
Attack vector Physical
Attack complexity Low
Privileges required None
User interaction None
Scope Unchanged
Confidentiality High
Integrity impact High
Availability impact High
Vector CVSS:3.1/AV:P/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H