CVE-2021-27379

Name: CVE-2021-27379
Creator: NVD / NIST
Published: 2021-02-18T17:15:15.867+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

HIGHCVSS 7.8/10EPSS 0.36%

Last modified Jun 17, 2026

CVE-2021-27379 is a high-severity vulnerability rated 7.8/10 on the CVSS scale. 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. EPSS estimates a 0.36% chance of exploitation in the next 30 days.

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.

Metrics

CVSS 3.1

7.8/10

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

EPSS Probability

0.36%

27.5th percentile

Probability of exploitation in the next 30 days. Learn more

Affected Software

Vendor	Product	Versions
Xen	Xen	>= 3.2.0, < 4.12.0
Debian	Debian Linux	10.0

References

http://www.openwall.com/lists/oss-security/2021/02/23/1Mailing List, Third Party Advisory
http://xenbits.xen.org/xsa/advisory-366.htmlMitigation, Patch, Vendor Advisory
https://www.debian.org/security/2021/dsa-4888Third Party Advisory
https://xenbits.xen.org/xsa/advisory-366.htmlPatch, Vendor Advisory
http://www.openwall.com/lists/oss-security/2021/02/23/1Mailing List, Third Party Advisory
http://xenbits.xen.org/xsa/advisory-366.htmlMitigation, Patch, Vendor Advisory
https://www.debian.org/security/2021/dsa-4888Third Party Advisory
https://xenbits.xen.org/xsa/advisory-366.htmlPatch, Vendor Advisory

Timeline

Published: Feb 18, 2021
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2021-27379?

How severe is CVE-2021-27379?

CVE-2021-27379 has a CVSS score of 7.8/10 (HIGH severity). The EPSS model estimates a 0.36% probability of exploitation in the next 30 days.

How do I fix CVE-2021-27379?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2021-27379?

Run a free Strix scan to check your systems for this vulnerability.

Scan your code now

Source: NVD / NIST