CVE-2021-20196

Name: CVE-2021-20196
Creator: NVD / NIST
Published: 2021-05-26T22:15:07.907+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

MEDIUMCVSS 6.5/10EPSS 0.48%

Last modified Jun 17, 2026

CVE-2021-20196 is a medium-severity vulnerability rated 6.5/10 on the CVSS scale. A NULL pointer dereference flaw was found in the floppy disk emulator of QEMU. This issue occurs while processing read/write ioport commands if the selected floppy drive is not initialized with a block device. EPSS estimates a 0.48% chance of exploitation in the next 30 days.

Description

A NULL pointer dereference flaw was found in the floppy disk emulator of QEMU. This issue occurs while processing read/write ioport commands if the selected floppy drive is not initialized with a block device. This flaw allows a privileged guest user to crash the QEMU process on the host, resulting in a denial of service. The highest threat from this vulnerability is to system availability.

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

0.48%

37.7th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

Affected Software

Vendor	Product	Versions
Qemu	Qemu	5.2.0
Debian	Debian Linux	9.0
Debian	Debian Linux	10.0

References

https://bugs.launchpad.net/qemu/+bug/1912780Exploit, Patch, 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://security.netapp.com/advisory/ntap-20210708-0004/Third Party Advisory
https://www.openwall.com/lists/oss-security/2021/01/28/1Mailing List, Patch, Third Party Advisory
https://bugs.launchpad.net/qemu/+bug/1912780Exploit, Patch, 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://security.netapp.com/advisory/ntap-20210708-0004/Third Party Advisory
https://www.openwall.com/lists/oss-security/2021/01/28/1Mailing List, Patch, Third Party Advisory

Timeline

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

Frequently Asked Questions

What is CVE-2021-20196?

How severe is CVE-2021-20196?

CVE-2021-20196 has a CVSS score of 6.5/10 (MEDIUM severity). The EPSS model estimates a 0.48% probability of exploitation in the next 30 days.

How do I fix CVE-2021-20196?

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-2021-20196?

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

Scan your code now

Source: NVD / NIST