CVE-2021-3975

Name: CVE-2021-3975
Creator: NVD / NIST
Published: 2022-08-23T20:15:08.427+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

MEDIUMCVSS 6.5/10EPSS 1.22%

Last modified Jun 17, 2026

CVE-2021-3975 is a medium-severity vulnerability rated 6.5/10 on the CVSS scale. A use-after-free flaw was found in libvirt. The qemuMonitorUnregister() function in qemuProcessHandleMonitorEOF is called using multiple threads without being adequately protected by a monitor lock. EPSS estimates a 1.22% chance of exploitation in the next 30 days.

Description

A use-after-free flaw was found in libvirt. The qemuMonitorUnregister() function in qemuProcessHandleMonitorEOF is called using multiple threads without being adequately protected by a monitor lock. This flaw could be triggered by the virConnectGetAllDomainStats API when the guest is shutting down. An unprivileged client with a read-only connection could use this flaw to perform a denial of service attack by causing the libvirt daemon to crash.

Metrics

CVSS 3.1

6.5/10

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

EPSS Probability

1.22%

64.8th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

Affected Software

Vendor	Product	Versions
Redhat	Libvirt	< 7.1.0
Canonical	Ubuntu Linux	21.10
Fedoraproject	Fedora	35
Redhat	Enterprise Linux	8.0
Redhat	Enterprise Linux Eus	8.6
Redhat	Enterprise Linux For Ibm Z Systems	8.0
Redhat	Enterprise Linux For Ibm Z Systems Eus	8.6
Redhat	Enterprise Linux For Power Little Endian	8.0
Redhat	Enterprise Linux For Power Little Endian Eus	8.6
Redhat	Enterprise Linux Server For Power Little Endian Update Services For Sap Solutions	8.6
Redhat	Enterprise Linux Server Tus	8.6
Redhat	Codeready Linux Builder	All versions
Debian	Debian Linux	10.0
Debian	Debian Linux	11.0
Netapp	Ontap Select Deploy Administration Utility	All versions

References

https://access.redhat.com/security/cve/CVE-2021-3975Issue Tracking, Third Party Advisory
https://bugzilla.redhat.com/show_bug.cgi?id=2024326Issue Tracking, Patch, Third Party Advisory
https://github.com/libvirt/libvirt/commit/1ac703a7d0789e46833f4013a3876c2e3af18ec7Patch, Third Party Advisory
https://lists.debian.org/debian-lts-announce/2024/04/msg00000.html
https://security.netapp.com/advisory/ntap-20221201-0002/Third Party Advisory
https://ubuntu.com/security/CVE-2021-3975Patch, Third Party Advisory
https://access.redhat.com/security/cve/CVE-2021-3975Issue Tracking, Third Party Advisory
https://bugzilla.redhat.com/show_bug.cgi?id=2024326Issue Tracking, Patch, Third Party Advisory
https://github.com/libvirt/libvirt/commit/1ac703a7d0789e46833f4013a3876c2e3af18ec7Patch, Third Party Advisory
https://lists.debian.org/debian-lts-announce/2024/04/msg00000.html
https://security.netapp.com/advisory/ntap-20221201-0002/Third Party Advisory
https://ubuntu.com/security/CVE-2021-3975Patch, Third Party Advisory

Timeline

Published: Aug 23, 2022
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2021-3975?

How severe is CVE-2021-3975?

CVE-2021-3975 has a CVSS score of 6.5/10 (MEDIUM severity). The EPSS model estimates a 1.22% probability of exploitation in the next 30 days.

How do I fix CVE-2021-3975?

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-2021-3975?

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

Scan your code now

Source: NVD / NIST