CVE-2021-27379

Severity: high (CVSS 7.8 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.4% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2021-02-18 · updated 2026-06-17

Description

An issue was discovered in Xen through 4.11.x, allowing x86 Intel HVM guest OS users to achieve unintended read/write DMA access, and possibly cause a denial of service (host OS crash) or gain privileges. This occurs because a backport missed a flush, and thus IOMMU updates were not always correct. NOTE: this issue exists because of an incomplete fix for CVE-2020-15565.

Affected products

Debian Linux: 10.0
xen: from 3.2.0 before 4.12.0 — fixed in 4.12.0

How to fix

Upgrade to a fixed version: xen 4.12.0. Check the vendor advisory for mitigations.

References

http://www.openwall.com/lists/oss-security/2021/02/23/1
http://xenbits.xen.org/xsa/advisory-366.html
https://www.debian.org/security/2021/dsa-4888
https://xenbits.xen.org/xsa/advisory-366.html
http://www.openwall.com/lists/oss-security/2021/02/23/1
http://xenbits.xen.org/xsa/advisory-366.html
https://www.debian.org/security/2021/dsa-4888
https://xenbits.xen.org/xsa/advisory-366.html

Get alerted when CVE-2021-27379 or the next vulnerability affects your stack