CVE-2021-20196

Severity: medium (CVSS 6.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.5% probability of exploitation in the next 30 days
Public exploit or detection template: yes
Published: 2021-05-26 · updated 2026-06-17
Weakness: CWE-476

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.

Affected products

Debian Linux: 9.0, 10.0
QEMU: 5.2.0

References

https://bugs.launchpad.net/qemu/+bug/1912780
https://lists.debian.org/debian-lts-announce/2022/04/msg00002.html
https://lists.debian.org/debian-lts-announce/2022/09/msg00008.html
https://security.netapp.com/advisory/ntap-20210708-0004/
https://www.openwall.com/lists/oss-security/2021/01/28/1
https://bugs.launchpad.net/qemu/+bug/1912780
https://lists.debian.org/debian-lts-announce/2022/04/msg00002.html
https://lists.debian.org/debian-lts-announce/2022/09/msg00008.html
https://security.netapp.com/advisory/ntap-20210708-0004/
https://www.openwall.com/lists/oss-security/2021/01/28/1

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