CVE-2021-3682

Name: CVE-2021-3682
Creator: NVD / NIST
Published: 2021-08-05T20:15:09.963+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

HIGHCVSS 8.5/10EPSS 2.90%

Last modified Jun 17, 2026

CVE-2021-3682 is a high-severity vulnerability rated 8.5/10 on the CVSS scale. A flaw was found in the USB redirector device emulation of QEMU in versions prior to 6.1.0-rc2. It occurs when dropping packets during a bulk transfer from a SPICE client due to the packet queue being full. EPSS estimates a 2.90% chance of exploitation in the next 30 days.

Description

A flaw was found in the USB redirector device emulation of QEMU in versions prior to 6.1.0-rc2. It occurs when dropping packets during a bulk transfer from a SPICE client due to the packet queue being full. A malicious SPICE client could use this flaw to make QEMU call free() with faked heap chunk metadata, resulting in a crash of QEMU or potential code execution with the privileges of the QEMU process on the host.

Metrics

CVSS 3.1

8.5/10

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

EPSS Probability

2.90%

85.2th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

Affected Software

Vendor	Product	Versions	Update
Qemu	Qemu	< 6.1.0	—
Qemu	Qemu	6.1.0	Rc1
Redhat	Enterprise Linux	8.0	—
Debian	Debian Linux	9.0	—
Debian	Debian Linux	10.0	—
Debian	Debian Linux	11.0	—

References

https://bugzilla.redhat.com/show_bug.cgi?id=1989651Issue Tracking, Patch, Third Party Advisory
https://lists.debian.org/debian-lts-announce/2021/09/msg00000.htmlThird Party Advisory
https://lists.debian.org/debian-lts-announce/2022/09/msg00008.htmlMailing List, Third Party Advisory
https://security.gentoo.org/glsa/202208-27Third Party Advisory
https://security.netapp.com/advisory/ntap-20210902-0006/Third Party Advisory
https://www.debian.org/security/2021/dsa-4980Third Party Advisory
https://bugzilla.redhat.com/show_bug.cgi?id=1989651Issue Tracking, Patch, Third Party Advisory
https://lists.debian.org/debian-lts-announce/2021/09/msg00000.htmlThird Party Advisory
https://lists.debian.org/debian-lts-announce/2022/09/msg00008.htmlMailing List, Third Party Advisory
https://security.gentoo.org/glsa/202208-27Third Party Advisory
https://security.netapp.com/advisory/ntap-20210902-0006/Third Party Advisory
https://www.debian.org/security/2021/dsa-4980Third Party Advisory

Timeline

Published: Aug 5, 2021
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2021-3682?

How severe is CVE-2021-3682?

CVE-2021-3682 has a CVSS score of 8.5/10 (HIGH severity). The EPSS model estimates a 2.90% probability of exploitation in the next 30 days.

How do I fix CVE-2021-3682?

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-2021-3682?

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

Scan your code now

Source: NVD / NIST