CVE-2021-3527

Name: CVE-2021-3527
Creator: NVD / NIST
Published: 2021-05-26T22:15:08.267+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

MEDIUMCVSS 5.5/10EPSS 0.37%

Last modified Jun 17, 2026

CVE-2021-3527 is a medium-severity vulnerability rated 5.5/10 on the CVSS scale. A flaw was found in the USB redirector device (usb-redir) of QEMU. Small USB packets are combined into a single, large transfer request, to reduce the overhead and improve performance. EPSS estimates a 0.37% chance of exploitation in the next 30 days.

Description

A flaw was found in the USB redirector device (usb-redir) of QEMU. Small USB packets are combined into a single, large transfer request, to reduce the overhead and improve performance. The combined size of the bulk transfer is used to dynamically allocate a variable length array (VLA) on the stack without proper validation. Since the total size is not bounded, a malicious guest could use this flaw to influence the array length and cause the QEMU process to perform an excessive allocation on the stack, resulting in a denial of service.

Metrics

CVSS 3.1

5.5/10

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

EPSS Probability

0.37%

28.9th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

Affected Software

Vendor	Product	Versions
Qemu	Qemu	<= 6.0.0
Redhat	Enterprise Linux	8.0
Debian	Debian Linux	9.0
Debian	Debian Linux	10.0

References

https://bugzilla.redhat.com/show_bug.cgi?id=1955695Issue Tracking, Patch, Third Party Advisory
https://gitlab.com/qemu-project/qemu/-/commit/05a40b172e4d691371534828078be47e7fff524cPatch, Third Party Advisory
https://gitlab.com/qemu-project/qemu/-/commit/7ec54f9eb62b5d177e30eb8b1cad795a5f8d8986Patch, Third Party Advisory
https://lists.debian.org/debian-lts-announce/2021/09/msg00000.htmlMailing List, Third 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-20210708-0008/Third Party Advisory
https://www.openwall.com/lists/oss-security/2021/05/05/5Mailing List, Patch, Third Party Advisory
https://bugzilla.redhat.com/show_bug.cgi?id=1955695Issue Tracking, Patch, Third Party Advisory
https://gitlab.com/qemu-project/qemu/-/commit/05a40b172e4d691371534828078be47e7fff524cPatch, Third Party Advisory
https://gitlab.com/qemu-project/qemu/-/commit/7ec54f9eb62b5d177e30eb8b1cad795a5f8d8986Patch, Third Party Advisory
https://lists.debian.org/debian-lts-announce/2021/09/msg00000.htmlMailing List, Third 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-20210708-0008/Third Party Advisory
https://www.openwall.com/lists/oss-security/2021/05/05/5Mailing List, Patch, Third Party Advisory

Timeline

Published: May 26, 2021
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2021-3527?

How severe is CVE-2021-3527?

CVE-2021-3527 has a CVSS score of 5.5/10 (MEDIUM severity). The EPSS model estimates a 0.37% probability of exploitation in the next 30 days.

How do I fix CVE-2021-3527?

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-2021-3527?

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

Scan your code now

Source: NVD / NIST