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Fencer Vulns
medium 6.8

CVE-2021-28695 json

IOMMU page mapping issues on x86 T[his CNA information record relates to multiple CVEs; the text explains which aspects/vulnerabilities cor…

published 2021-08-27 5 y ago modified 2026-06-17 4 mo ago also EUVD-2021-15352

cvss
6.8
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
0.4%
EPSS 0.4% chance of exploitation in 30 days, percentile 31%
public exploits
0
none known

Summary

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).

Patch / fix

  • xen Debian 14, Debian 13, Debian 12 4.14.3-1

debian advisories DEBIAN-CVE-2021-28695

  • xen SLES 12 SP2-BCL 4.7.6_16-43.79.5
  • xen SLES for SAP 12 SP3, SLES 12 SP3-LTSS, SLES 12 SP3-BCL +3 more 4.9.4_20-3.91.1
  • xen SLES for SAP 12 SP4, SLES 12 SP4-LTSS, OpenStack Cloud Crowbar 9 +1 more 4.11.4_20-2.60.1
  • xen SLES for SAP 15, SLE High Performance Computing 15-LTSS, SLE High Performance Computing 15-ESPOS 4.10.4_26-3.61.1
  • xen SLES for SAP 15 SP1, SLES 15 SP1-LTSS, SLES 15 SP1-BCL +6 more 4.12.4_12-3.52.1
  • xen SLES for SAP 12 SP5, SLES 12 SP5, SLE Software Development Kit 12 SP5 4.12.4_12-3.49.1
  • xen SLE Module for Server Applications 15 SP3, SLE Module for Basesystem 15 SP3 4.14.2_04-3.9.1
  • xen SLE Module for Server Applications 15 SP2, SLE Module for Basesystem 15 SP2, SLE Micro 5.0 4.13.3_02-3.34.1

suse advisories SUSE-SU-2021:3322-1SUSE-SU-2021:2957-1SUSE-SU-2021:2955-1SUSE-SU-2021:2943-1SUSE-SU-2021:2925-1SUSE-SU-2021:2924-1

  • xen openSUSE Leap 15.2 4.13.3_02-lp152.2.27.1
  • xen openSUSE Leap 15.3 4.14.2_04-3.9.1

opensuse advisories openSUSE-SU-2021:1236-1openSUSE-SU-2021:2923-1

  • xen Alpine 3.12, Alpine 3.11 4.13.3-r2
  • xen Alpine 3.13 4.14.2-r0
  • xen Alpine 3.24, Alpine 3.23, Alpine 3.22 +8 more 4.15.0-r2

alpine advisories ALPINE-CVE-2021-28695

Alpine secdb © Alpine Linux, from https://secdb.alpinelinux.org via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2021-28695 updated cvss 5.9

xen: discontinuous range is specified by firmware leads to vulnerability

  • Red Hat All currently supported Red Hat products
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

Exploit prediction

0.38% chance of exploitation in the next 30 days, higher than 31% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
NVD 3.1 6.8 CVSS:3.1/AV:P/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
NVD 2.0 4.6 AV:L/AC:L/Au:N/C:P/I:P/A:P

Affected products

  • Xen xen

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.