CVE-2021-20196

NameCVE-2021-20196
DescriptionA 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.
SourceCVE (at NVD; CERT, LWN, oss-sec, fulldisc, Red Hat, Ubuntu, Gentoo, SUSE bugzilla/CVE, GitHub advisories/code/issues, web search, more)
ReferencesDLA-2970-1, DLA-3099-1
Debian Bugs984453

Vulnerable and fixed packages

The table below lists information on source packages.

Source PackageReleaseVersionStatus
qemu (PTS)jessie, jessie (lts)1:2.1+dfsg-12+deb8u23fixed
stretch (security)1:2.8+dfsg-6+deb9u17fixed
stretch (lts), stretch1:2.8+dfsg-6+deb9u19fixed
buster1:3.1+dfsg-8+deb10u8vulnerable
buster (security)1:3.1+dfsg-8+deb10u12fixed
bullseye1:5.2+dfsg-11+deb11u3fixed
bullseye (security)1:5.2+dfsg-11+deb11u2vulnerable
bookworm1:7.2+dfsg-7+deb12u6fixed
trixie1:8.2.4+ds-1fixed
sid1:9.0.2+ds-1fixed

The information below is based on the following data on fixed versions.

PackageTypeReleaseFixed VersionUrgencyOriginDebian Bugs
qemusourcejessie(not affected)
qemusourcestretch1:2.8+dfsg-6+deb9u17DLA-2970-1
qemusourcebuster1:3.1+dfsg-8+deb10u9DLA-3099-1
qemusourcebullseye1:5.2+dfsg-11+deb11u3
qemusource(unstable)1:6.2+dfsg-1984453

Notes

https://bugzilla.redhat.com/show_bug.cgi?id=1919210
https://bugs.launchpad.net/qemu/+bug/1912780
https://gitlab.com/qemu-project/qemu/-/issues/338
https://lists.nongnu.org/archive/html/qemu-devel/2021-01/msg05986.html
Fixed by: https://gitlab.com/qemu-project/qemu/-/commit/1ab95af033a419e7a64e2d58e67dd96b20af5233 (v6.2.0-rc4)
[jessie] - qemu <not-affected> (Vulnerable code introduced later)

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