VulnerabilityModified
CVE-2021-26933
On Arm, a guest is allowed to control whether memory accesses are bypassing the cache.
MEDIUM 5.5EPSS 0.33%
Does this matter?
Lower severity and a low EPSS score (0.33%). Track it; it rarely justifies an emergency change on its own.
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 3.1
- 5.5 MEDIUMCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N
- EPSS
- 0.33% probability · 26th percentile
- CISA KEV
- Not listed
- Affected
- xen/xen · fedoraproject/fedora · debian/debian linux
- Source
- cve@mitre.org
References
- http://xenbits.xen.org/xsa/advisory-364.htmlPatch, Vendor Advisory
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/4GELN5E6MDR5KQBJF5M5COUUED3YFZTD/
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/EOAJBVAVR6RSCUCHNXPVSNRPSFM7INMP/
- https://www.debian.org/security/2021/dsa-4888Third Party Advisory
- http://xenbits.xen.org/xsa/advisory-364.htmlPatch, Vendor Advisory
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/4GELN5E6MDR5KQBJF5M5COUUED3YFZTD/
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/EOAJBVAVR6RSCUCHNXPVSNRPSFM7INMP/
- https://www.debian.org/security/2021/dsa-4888Third Party Advisory
Source: NVD record, EPSS from FIRST.org, KEV from CISA. Refreshed daily.