CVE-2021-28696 Information

Description

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 Vector

CVSS:3.1/AV:P/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Reference

https://xenbits.xenproject.org/xsa/advisory-378.txt http://www.openwall.com/lists/oss-security/2021/09/01/1 http://www.openwall.com/lists/oss-security/2021/09/01/5 http://www.openwall.com/lists/oss-security/2021/09/01/6 https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/FZCNPSRPGFCQRYE2BI4D4Q4SCE56ANV2/ https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/LPRVHW4J4ZCPPOHZEWP5MOJT7XDGFFPJ/ https://www.debian.org/security/2021/dsa-4977 https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/2VQCFAPBNGBBAOMJZG6QBREOG5IIDZID/

Attack Complexity

LOW

Privileges Required

NONE

User Interaction Required

NONE

Scope

NONE

Confidentiality Impact

UNCHANGED

Integrity Impact

HIGH

Availability Impact

HIGH

Base Score

HIGH

Base Severity

6.8