CVE-2021-28696

2021-08-2718:46:33

XEN

www.cve.org

iommu

page mapping

x86

memory regions

acpi tables

translation phase

device mapping

amd

intel

firmware

identity mappings

physical device

AI Score

7.1

Confidence

High

EPSS

0.002

Percentile

52.2%

JSON

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).

CNA Affected

[
  {
    "product": "xen",
    "vendor": "Xen",
    "versions": [
      {
        "status": "affected",
        "version": "4.11.x"
      }
    ]
  },
  {
    "product": "xen",
    "vendor": "Xen",
    "versions": [
      {
        "status": "affected",
        "version": "xen-unstable"
      }
    ]
  },
  {
    "product": "xen",
    "vendor": "Xen",
    "versions": [
      {
        "status": "affected",
        "version": "4.12.x"
      }
    ]
  },
  {
    "product": "xen",
    "vendor": "Xen",
    "versions": [
      {
        "status": "affected",
        "version": "4.14.x"
      }
    ]
  },
  {
    "product": "xen",
    "vendor": "Xen",
    "versions": [
      {
        "status": "affected",
        "version": "4.15.x"
      }
    ]
  },
  {
    "product": "xen",
    "vendor": "Xen",
    "versions": [
      {
        "status": "affected",
        "version": "4.13.x"
      }
    ]
  }
]