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Vulnerability · Published Feb 17, 2021 · Assigned by mitre

CVE-2021-26933

Medium 5.5

In plain English

A medium-severity security flaw in the xen package (Alpine). There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.3% (higher than 26% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.

Severity (CVSS NVD)5.5Medium
Exploit odds (30 days)0.3%top 74.1% of all CVEs
Exploited in the wildNo reportsnot in CISA KEV
Attack toolingNoneno public tooling known

Official 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.

Affected packages & fixed versions

EcosystemPackageFixed inAdvisory
Alpine:v3.20xen4.14.1-r3ALPINE-CVE-2021-26933
Alpine:v3.21xen4.14.1-r3ALPINE-CVE-2021-26933
Alpine:v3.22xen4.14.1-r3ALPINE-CVE-2021-26933
Alpine:v3.23xen4.14.1-r3ALPINE-CVE-2021-26933
Alpine:v3.24xen4.14.1-r3ALPINE-CVE-2021-26933
Debian:12xen4.14.1+11-gb0b734a8b3-1DEBIAN-CVE-2021-26933
Debian:13xen4.14.1+11-gb0b734a8b3-1DEBIAN-CVE-2021-26933
Debian:14xen4.14.1+11-gb0b734a8b3-1DEBIAN-CVE-2021-26933
Ubuntu:22.04:LTSxenno fix listedUBUNTU-CVE-2021-26933
Ubuntu:24.04:LTSxenno fix listedUBUNTU-CVE-2021-26933
Ubuntu:25.10xenno fix listedUBUNTU-CVE-2021-26933
Ubuntu:26.04:LTSxenno fix listedUBUNTU-CVE-2021-26933
Ubuntu:26.10xenno fix listedUBUNTU-CVE-2021-26933

Affected products (as reported)

VendorProductVersions
n/a n/a n/a

References