CVE-2021-26933
MEDIUMXen 4.9-4.14.x - Information Exposure via Cache Bypass Timing
Title source: llmDescription
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.
References (4)
Core 4
Core References
Patch, Vendor Advisory x_refsource_misc
http://xenbits.xen.org/xsa/advisory-364.html
Mailing List, Third Party Advisory vendor-advisory
x_refsource_fedora
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/4GELN5E6MDR5KQBJF5M5COUUED3YFZTD/
Mailing List, Third Party Advisory vendor-advisory
x_refsource_fedora
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/EOAJBVAVR6RSCUCHNXPVSNRPSFM7INMP/
Third Party Advisory vendor-advisory
x_refsource_debian
https://www.debian.org/security/2021/dsa-4888
Scores
CVSS v3
5.5
EPSS
0.0008
EPSS Percentile
23.6%
Attack Vector
LOCAL
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N
Details
Status
published
Products (4)
debian/debian_linux
10.0
fedoraproject/fedora
32
fedoraproject/fedora
33
xen/xen
4.9.0 - 4.14.1
Published
Feb 17, 2021
Tracked Since
Feb 18, 2026