CVE-2021-28701 Information

Description

Another race in XENMAPSPACE_grant_table handling Guests are permitted access to certain Xen-owned pages of memory. The majority of such pages remain allocated / associated with a guest for its entire lifetime. Grant table v2 status pages however are de-allocated when a guest switches (back) from v2 to v1. Freeing such pages requires that the hypervisor enforce that no parallel request can result in the addition of a mapping of such a page to a guest. That enforcement was missing allowing guests to retain access to pages that were freed and perhaps re-used for other purposes. Unfortunately when XSA-379 was being prepared this similar issue was not noticed.

CVSS Vector

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

Reference

https://xenbits.xenproject.org/xsa/advisory-384.txt http://xenbits.xen.org/xsa/advisory-384.html http://www.openwall.com/lists/oss-security/2021/09/08/2 https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/L4MI3MQAPGILCLXBGQWPZHGE3ALSO4ZU/ https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/CEHZLIR5DFYYQBH55AERWHLO54OFU42C/ https://www.debian.org/security/2021/dsa-4977 https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/3HEHUIUWSSMCQGQY3GWX4J2SZGYP5W2Z/

Attack Complexity

HIGH

Privileges Required

LOW

User Interaction Required

LOW

Scope

NONE

Confidentiality Impact

CHANGED

Integrity Impact

HIGH

Availability Impact

HIGH

Base Score

HIGH

Base Severity

7.8