medium
6.8
Advisory Published
Updated

CVE-2021-28694

First published: Fri Aug 27 2021(Updated: )

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).

Credit: security@xen.org

Affected SoftwareAffected VersionHow to fix
debian/xen<=4.11.4+107-gef32c7afa2-1
4.14.6-1
4.14.5+94-ge49571868d-1
4.17.1+2-gb773c48e36-1
4.17.2+55-g0b56bed864-1
Xen XAPI
Fedora=33
Fedora=34
Fedora=35
Debian=11.0

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Reference Links

Frequently Asked Questions

  • What is the severity of CVE-2021-28694?

    CVE-2021-28694 is rated as a high severity vulnerability due to its impact on system memory management.

  • How do I fix CVE-2021-28694?

    To fix CVE-2021-28694, update to the recommended versions of the Xen hypervisor or affected operating systems as specified in the advisory.

  • Which software is affected by CVE-2021-28694?

    CVE-2021-28694 affects versions of the Xen hypervisor as well as particular releases of Fedora and Debian.

  • What does CVE-2021-28694 involve?

    CVE-2021-28694 involves IOMMU page mapping issues that can potentially lead to unauthorized memory access.

  • Is CVE-2021-28694 exploitable remotely?

    CVE-2021-28694 is potentially exploitable by local users on the affected systems, depending on the specific configurations in place.

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