CVE-2021-20263

Name: CVE-2021-20263
Creator: NVD / NIST
Published: 2021-03-09T18:15:15.593+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

LOWCVSS 3.3/10EPSS 0.38%

Last modified Jun 17, 2026

CVE-2021-20263 is a low-severity vulnerability rated 3.3/10 on the CVSS scale. A flaw was found in the virtio-fs shared file system daemon (virtiofsd) of QEMU. The new 'xattrmap' option may cause the 'security.capability' xattr in the guest to not drop on file write, potentially leading to a modified, privileged executable in the guest. EPSS estimates a 0.38% chance of exploitation in the next 30 days.

Description

A flaw was found in the virtio-fs shared file system daemon (virtiofsd) of QEMU. The new 'xattrmap' option may cause the 'security.capability' xattr in the guest to not drop on file write, potentially leading to a modified, privileged executable in the guest. In rare circumstances, this flaw could be used by a malicious user to elevate their privileges within the guest.

Metrics

CVSS 3.1

3.3/10

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

EPSS Probability

0.38%

29.5th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

Affected Software

Vendor	Product	Versions
Qemu	Qemu	>= 5.0.0, < 5.2.50

References

https://bugzilla.redhat.com/show_bug.cgi?id=1933668Issue Tracking, Patch, Third Party Advisory
https://security.gentoo.org/glsa/202208-27Third Party Advisory
https://security.netapp.com/advisory/ntap-20210507-0002/Third Party Advisory
https://www.openwall.com/lists/oss-security/2021/03/08/1Mailing List, Patch, Third Party Advisory
https://bugzilla.redhat.com/show_bug.cgi?id=1933668Issue Tracking, Patch, Third Party Advisory
https://security.gentoo.org/glsa/202208-27Third Party Advisory
https://security.netapp.com/advisory/ntap-20210507-0002/Third Party Advisory
https://www.openwall.com/lists/oss-security/2021/03/08/1Mailing List, Patch, Third Party Advisory

Timeline

Published: Mar 9, 2021
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2021-20263?

How severe is CVE-2021-20263?

CVE-2021-20263 has a CVSS score of 3.3/10 (LOW severity). The EPSS model estimates a 0.38% probability of exploitation in the next 30 days.

How do I fix CVE-2021-20263?

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-2021-20263?

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

Scan your code now

Source: NVD / NIST