CVE-2021-26933 Affecting xen package, versions <4.11.4+99-g8bce4698f6-1


Severity

Recommended
0.0
medium
0
10

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Threat Intelligence

EPSS
0.05% (18th percentile)

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  • Snyk IDSNYK-DEBIAN10-XEN-1075452
  • published17 Feb 2021
  • disclosed17 Feb 2021

Introduced: 17 Feb 2021

CVE-2021-26933  (opens in a new tab)

How to fix?

Upgrade Debian:10 xen to version 4.11.4+99-g8bce4698f6-1 or higher.

NVD Description

Note: Versions mentioned in the description apply only to the upstream xen package and not the xen package as distributed by Debian. See How to fix? for Debian:10 relevant fixed versions and status.

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 Scores

version 3.1