CVE-2021-3748

Name: CVE-2021-3748
Creator: NVD / NIST
Published: 2022-03-23T20:15:09.893+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

HIGHCVSS 7.5/10EPSS 0.53%

Last modified Jun 17, 2026

CVE-2021-3748 is a high-severity vulnerability rated 7.5/10 on the CVSS scale. A use-after-free vulnerability was found in the virtio-net device of QEMU. It could occur when the descriptor's address belongs to the non direct access region, due to num_buffers being set after the virtqueue elem has been unmapped. EPSS estimates a 0.53% chance of exploitation in the next 30 days.

Description

A use-after-free vulnerability was found in the virtio-net device of QEMU. It could occur when the descriptor's address belongs to the non direct access region, due to num_buffers being set after the virtqueue elem has been unmapped. A malicious guest could use this flaw to crash QEMU, resulting in a denial of service condition, or potentially execute code on the host with the privileges of the QEMU process.

Metrics

CVSS 3.1

7.5/10

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

EPSS Probability

0.53%

40.5th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

Affected Software

Vendor	Product	Versions
Qemu	Qemu	>= 0.10.0, < 6.2.0
Debian	Debian Linux	9.0
Debian	Debian Linux	10.0
Canonical	Ubuntu Linux	18.04
Canonical	Ubuntu Linux	20.04
Canonical	Ubuntu Linux	21.10
Fedoraproject	Fedora	34
Redhat	Enterprise Linux	8.0
Redhat	Enterprise Linux Advanced Virtualization Eus	8.4

References

https://bugzilla.redhat.com/show_bug.cgi?id=1998514Issue Tracking, Patch, Third Party Advisory
https://github.com/qemu/qemu/commit/bedd7e93d01961fcb16a97ae45d93acf357e11f6Patch, Third Party Advisory
https://lists.debian.org/debian-lts-announce/2022/04/msg00002.htmlMailing List, Third Party Advisory
https://lists.debian.org/debian-lts-announce/2022/09/msg00008.htmlMailing List, Third Party Advisory
https://lists.nongnu.org/archive/html/qemu-devel/2021-09/msg00388.htmlMailing List, Patch, Third Party Advisory
https://security.gentoo.org/glsa/202208-27Third Party Advisory
https://security.netapp.com/advisory/ntap-20220425-0004/Third Party Advisory
https://ubuntu.com/security/CVE-2021-3748Patch, Third Party Advisory
https://bugzilla.redhat.com/show_bug.cgi?id=1998514Issue Tracking, Patch, Third Party Advisory
https://github.com/qemu/qemu/commit/bedd7e93d01961fcb16a97ae45d93acf357e11f6Patch, Third Party Advisory
https://lists.debian.org/debian-lts-announce/2022/04/msg00002.htmlMailing List, Third Party Advisory
https://lists.debian.org/debian-lts-announce/2022/09/msg00008.htmlMailing List, Third Party Advisory
https://lists.nongnu.org/archive/html/qemu-devel/2021-09/msg00388.htmlMailing List, Patch, Third Party Advisory
https://security.gentoo.org/glsa/202208-27Third Party Advisory
https://security.netapp.com/advisory/ntap-20220425-0004/Third Party Advisory
https://ubuntu.com/security/CVE-2021-3748Patch, Third Party Advisory

Timeline

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

Frequently Asked Questions

What is CVE-2021-3748?

How severe is CVE-2021-3748?

CVE-2021-3748 has a CVSS score of 7.5/10 (HIGH severity). The EPSS model estimates a 0.53% probability of exploitation in the next 30 days.

How do I fix CVE-2021-3748?

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-2021-3748?

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

Scan your code now

Source: NVD / NIST