CVE-2021-4145

Name: CVE-2021-4145
Creator: NVD / NIST
Published: 2022-01-25T20:15:08.657+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

MEDIUMCVSS 6.5/10EPSS 0.39%

Last modified Jun 17, 2026

CVE-2021-4145 is a medium-severity vulnerability rated 6.5/10 on the CVSS scale. A NULL pointer dereference issue was found in the block mirror layer of QEMU in versions prior to 6.2.0. The `self` pointer is dereferenced in mirror_wait_on_conflicts() without ensuring that it's not NULL. EPSS estimates a 0.39% chance of exploitation in the next 30 days.

Description

A NULL pointer dereference issue was found in the block mirror layer of QEMU in versions prior to 6.2.0. The `self` pointer is dereferenced in mirror_wait_on_conflicts() without ensuring that it's not NULL. A malicious unprivileged user within the guest could use this flaw to crash the QEMU process on the host when writing data reaches the threshold of mirroring node.

Metrics

CVSS 3.1

6.5/10

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

EPSS Probability

0.39%

30.8th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

Affected Software

Vendor	Product	Versions
Qemu	Qemu	6.1.0
Redhat	Enterprise Linux	8.0

References

https://bugzilla.redhat.com/show_bug.cgi?id=2034602Issue Tracking, Patch, Third Party Advisory
https://gitlab.com/qemu-project/qemu/-/commit/66fed30c9cd11854fc878a4eceb507e915d7c9cdPatch, Third Party Advisory
https://security.gentoo.org/glsa/202208-27Third Party Advisory
https://security.netapp.com/advisory/ntap-20220311-0004/Third Party Advisory
https://bugzilla.redhat.com/show_bug.cgi?id=2034602Issue Tracking, Patch, Third Party Advisory
https://gitlab.com/qemu-project/qemu/-/commit/66fed30c9cd11854fc878a4eceb507e915d7c9cdPatch, Third Party Advisory
https://security.gentoo.org/glsa/202208-27Third Party Advisory
https://security.netapp.com/advisory/ntap-20220311-0004/Third Party Advisory

Timeline

Published: Jan 25, 2022
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2021-4145?

How severe is CVE-2021-4145?

CVE-2021-4145 has a CVSS score of 6.5/10 (MEDIUM severity). The EPSS model estimates a 0.39% probability of exploitation in the next 30 days.

How do I fix CVE-2021-4145?

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-2021-4145?

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

Scan your code now

Source: NVD / NIST