CVE-2021-28695 Affecting xen package, versions <4.15.0-r2


Severity

Recommended
0.0
medium
0
10

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Threat Intelligence

EPSS
0.27% (68th percentile)

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  • Snyk IDSNYK-ALPINE316-XEN-2845208
  • published8 Sept 2021
  • disclosed27 Aug 2021

Introduced: 27 Aug 2021

CVE-2021-28695  (opens in a new tab)

How to fix?

Upgrade Alpine:3.16 xen to version 4.15.0-r2 or higher.

NVD Description

Note: Versions mentioned in the description apply only to the upstream xen package and not the xen package as distributed by Alpine. See How to fix? for Alpine:3.16 relevant fixed versions and status.

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).

CVSS Scores

version 3.1