CVE-2021-26933
xen - security update
5.5
MEDIUM
CVSS 3.1
EPSS 0.08%
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.
How to fix CVE-2021-26933
To remediate CVE-2021-26933, upgrade the affected package to a fixed version below.
- —upgrade to 4.13.2-r5 or later
- —upgrade to 4.14.1+11-gb0b734a8b3-1 or later
- —upgrade to 4.11.4+99-g8bce4698f6-1 or later
Is CVE-2021-26933 being exploited?
Low — EPSS is 0.1%, meaning exploitation activity has not been observed at scale.
Affected packages (3)
- from 0, < 4.13.2-r5
- from 0, < 4.14.1+11-gb0b734a8b3-1
- from 0, < 4.11.4+99-g8bce4698f6-1
CVSS scores
| Source | Version | Severity | Vector |
|---|---|---|---|
| osv | CVSS 3.1 | MEDIUM5.5 | CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N |