CVE-2021-26933 Information

Description

An issue was discovered in Xen 4.9 through 4.14.x. On Arm a guest is allowed to control whether memory accesses are bypassing the cache. This means that Xen needs to ensure that all writes (such as the ones during scrubbing) have reached the memory before handing over the page to a guest. Unfortunately the operation to clean the cache is happening before checking if the page was scrubbed. Therefore there is no guarantee when all the writes will reach the memory.

CVSS Vector

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

Reference

http://xenbits.xen.org/xsa/advisory-364.html https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/EOAJBVAVR6RSCUCHNXPVSNRPSFM7INMP/ https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/4GELN5E6MDR5KQBJF5M5COUUED3YFZTD/ https://www.debian.org/security/2021/dsa-4888

Attack Complexity

LOW

Privileges Required

LOW

User Interaction Required

LOW

Scope

NONE

Confidentiality Impact

UNCHANGED

Integrity Impact

HIGH

Availability Impact

NONE

Base Score

NONE

Base Severity

5.5