Vulnerability · Published May 26, 2021 · Assigned by redhat

CVE-2021-20196

Medium 6.5

In plain English

A medium-severity null pointer dereference in qemu. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.5% (higher than 42% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.

Severity (CVSS NVD)6.5Medium
Exploit odds (30 days)0.5%top 58.5% of all CVEs
Exploited in the wildNo reportsnot in CISA KEV
Attack toolingNoneno public tooling known

Official 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 packages & fixed versions

EcosystemPackageFixed inAdvisory
AlmaLinux:8SLOF20210217-1.module_el8.6.0+2880+7d9e3703ALSA-2022:1759
AlmaLinux:8hivex1.3.18-23.module_el8.6.0+2880+7d9e3703ALSA-2022:1759
AlmaLinux:8hivex-devel1.3.18-23.module_el8.6.0+2880+7d9e3703ALSA-2022:1759
AlmaLinux:8libguestfs1:1.44.0-5.module_el8.6.0+2880+7d9e3703.almaALSA-2022:1759
AlmaLinux:8libguestfs-appliance1:1.44.0-5.module_el8.6.0+2880+7d9e3703.almaALSA-2022:1759
AlmaLinux:8libguestfs-bash-completion1:1.44.0-5.module_el8.6.0+2880+7d9e3703.almaALSA-2022:1759
AlmaLinux:8libguestfs-devel1:1.44.0-5.module_el8.6.0+2880+7d9e3703.almaALSA-2022:1759
AlmaLinux:8libguestfs-gfs21:1.44.0-5.module_el8.6.0+2880+7d9e3703.almaALSA-2022:1759
AlmaLinux:8libguestfs-gobject1:1.44.0-5.module_el8.6.0+2880+7d9e3703.almaALSA-2022:1759
AlmaLinux:8libguestfs-gobject-devel1:1.44.0-5.module_el8.6.0+2880+7d9e3703.almaALSA-2022:1759
AlmaLinux:8libguestfs-inspect-icons1:1.44.0-5.module_el8.6.0+2880+7d9e3703.almaALSA-2022:1759
AlmaLinux:8libguestfs-java1:1.44.0-5.module_el8.6.0+2880+7d9e3703.almaALSA-2022:1759
AlmaLinux:8libguestfs-java-devel1:1.44.0-5.module_el8.6.0+2880+7d9e3703.almaALSA-2022:1759
AlmaLinux:8libguestfs-javadoc1:1.44.0-5.module_el8.6.0+2880+7d9e3703.almaALSA-2022:1759
AlmaLinux:8libguestfs-man-pages-ja1:1.44.0-5.module_el8.6.0+2880+7d9e3703.almaALSA-2022:1759
AlmaLinux:8libguestfs-man-pages-uk1:1.44.0-5.module_el8.6.0+2880+7d9e3703.almaALSA-2022:1759
AlmaLinux:8libguestfs-rescue1:1.44.0-5.module_el8.6.0+2880+7d9e3703.almaALSA-2022:1759
AlmaLinux:8libguestfs-rsync1:1.44.0-5.module_el8.6.0+2880+7d9e3703.almaALSA-2022:1759
AlmaLinux:8libguestfs-tools1:1.44.0-5.module_el8.6.0+2880+7d9e3703.almaALSA-2022:1759
AlmaLinux:8libguestfs-tools-c1:1.44.0-5.module_el8.6.0+2880+7d9e3703.almaALSA-2022:1759
AlmaLinux:8libguestfs-winsupport8.6-1.module_el8.6.0+2880+7d9e3703ALSA-2022:1759
AlmaLinux:8libguestfs-xfs1:1.44.0-5.module_el8.6.0+2880+7d9e3703.almaALSA-2022:1759
AlmaLinux:8libiscsi1.18.0-8.module_el8.6.0+2880+7d9e3703ALSA-2022:1759
AlmaLinux:8libiscsi-devel1.18.0-8.module_el8.6.0+2880+7d9e3703ALSA-2022:1759
AlmaLinux:8libiscsi-utils1.18.0-8.module_el8.6.0+2880+7d9e3703ALSA-2022:1759
AlmaLinux:8libnbd1.6.0-5.module_el8.6.0+2880+7d9e3703ALSA-2022:1759
AlmaLinux:8libnbd-bash-completion1.6.0-5.module_el8.6.0+2880+7d9e3703ALSA-2022:1759
AlmaLinux:8libnbd-devel1.6.0-5.module_el8.6.0+2880+7d9e3703ALSA-2022:1759
AlmaLinux:8libtpms0.9.1-0.20211126git1ff6fe1f43.module_el8.6.0+2880+7d9e3703ALSA-2022:1759
AlmaLinux:8libtpms-devel0.9.1-0.20211126git1ff6fe1f43.module_el8.6.0+2880+7d9e3703ALSA-2022:1759
AlmaLinux:8libvirt8.0.0-5.module_el8.6.0+2880+7d9e3703ALSA-2022:1759
AlmaLinux:8libvirt-client8.0.0-5.module_el8.6.0+2880+7d9e3703ALSA-2022:1759
AlmaLinux:8libvirt-daemon8.0.0-5.module_el8.6.0+2880+7d9e3703ALSA-2022:1759
AlmaLinux:8libvirt-daemon-config-network8.0.0-5.module_el8.6.0+2880+7d9e3703ALSA-2022:1759
AlmaLinux:8libvirt-daemon-config-nwfilter8.0.0-5.module_el8.6.0+2880+7d9e3703ALSA-2022:1759
AlmaLinux:8libvirt-daemon-driver-interface8.0.0-5.module_el8.6.0+2880+7d9e3703ALSA-2022:1759
AlmaLinux:8libvirt-daemon-driver-network8.0.0-5.module_el8.6.0+2880+7d9e3703ALSA-2022:1759
AlmaLinux:8libvirt-daemon-driver-nodedev8.0.0-5.module_el8.6.0+2880+7d9e3703ALSA-2022:1759
AlmaLinux:8libvirt-daemon-driver-nwfilter8.0.0-5.module_el8.6.0+2880+7d9e3703ALSA-2022:1759
AlmaLinux:8libvirt-daemon-driver-qemu8.0.0-5.module_el8.6.0+2880+7d9e3703ALSA-2022:1759
AlmaLinux:8libvirt-daemon-driver-secret8.0.0-5.module_el8.6.0+2880+7d9e3703ALSA-2022:1759
AlmaLinux:8libvirt-daemon-driver-storage8.0.0-5.module_el8.6.0+2880+7d9e3703ALSA-2022:1759
AlmaLinux:8libvirt-daemon-driver-storage-core8.0.0-5.module_el8.6.0+2880+7d9e3703ALSA-2022:1759
AlmaLinux:8libvirt-daemon-driver-storage-disk8.0.0-5.module_el8.6.0+2880+7d9e3703ALSA-2022:1759
AlmaLinux:8libvirt-daemon-driver-storage-gluster8.0.0-5.module_el8.6.0+2880+7d9e3703ALSA-2022:1759
AlmaLinux:8libvirt-daemon-driver-storage-iscsi8.0.0-5.module_el8.6.0+2880+7d9e3703ALSA-2022:1759
AlmaLinux:8libvirt-daemon-driver-storage-iscsi-direct8.0.0-5.module_el8.6.0+2880+7d9e3703ALSA-2022:1759
AlmaLinux:8libvirt-daemon-driver-storage-logical8.0.0-5.module_el8.6.0+2880+7d9e3703ALSA-2022:1759
AlmaLinux:8libvirt-daemon-driver-storage-mpath8.0.0-5.module_el8.6.0+2880+7d9e3703ALSA-2022:1759
AlmaLinux:8libvirt-daemon-driver-storage-rbd8.0.0-5.module_el8.6.0+2880+7d9e3703ALSA-2022:1759
AlmaLinux:8libvirt-daemon-driver-storage-scsi8.0.0-5.module_el8.6.0+2880+7d9e3703ALSA-2022:1759
AlmaLinux:8libvirt-daemon-kvm8.0.0-5.module_el8.6.0+2880+7d9e3703ALSA-2022:1759
AlmaLinux:8libvirt-dbus1.3.0-2.module_el8.6.0+2880+7d9e3703ALSA-2022:1759
AlmaLinux:8libvirt-devel8.0.0-5.module_el8.6.0+2880+7d9e3703ALSA-2022:1759
AlmaLinux:8libvirt-docs8.0.0-5.module_el8.6.0+2880+7d9e3703ALSA-2022:1759
AlmaLinux:8libvirt-libs8.0.0-5.module_el8.6.0+2880+7d9e3703ALSA-2022:1759
AlmaLinux:8libvirt-lock-sanlock8.0.0-5.module_el8.6.0+2880+7d9e3703ALSA-2022:1759
AlmaLinux:8libvirt-nss8.0.0-5.module_el8.6.0+2880+7d9e3703ALSA-2022:1759
AlmaLinux:8libvirt-wireshark8.0.0-5.module_el8.6.0+2880+7d9e3703ALSA-2022:1759
AlmaLinux:8lua-guestfs1:1.44.0-5.module_el8.6.0+2880+7d9e3703.almaALSA-2022:1759
AlmaLinux:8nbdfuse1.6.0-5.module_el8.6.0+2880+7d9e3703ALSA-2022:1759
AlmaLinux:8nbdkit1.24.0-4.module_el8.6.0+2880+7d9e3703ALSA-2022:1759
AlmaLinux:8nbdkit-bash-completion1.24.0-4.module_el8.6.0+2880+7d9e3703ALSA-2022:1759
AlmaLinux:8nbdkit-basic-filters1.24.0-4.module_el8.6.0+2880+7d9e3703ALSA-2022:1759
AlmaLinux:8nbdkit-basic-plugins1.24.0-4.module_el8.6.0+2880+7d9e3703ALSA-2022:1759
AlmaLinux:8nbdkit-curl-plugin1.24.0-4.module_el8.6.0+2880+7d9e3703ALSA-2022:1759
AlmaLinux:8nbdkit-devel1.24.0-4.module_el8.6.0+2880+7d9e3703ALSA-2022:1759
AlmaLinux:8nbdkit-example-plugins1.24.0-4.module_el8.6.0+2880+7d9e3703ALSA-2022:1759
AlmaLinux:8nbdkit-gzip-filter1.24.0-4.module_el8.6.0+2880+7d9e3703ALSA-2022:1759
AlmaLinux:8nbdkit-gzip-plugin1.24.0-4.module_el8.6.0+2880+7d9e3703ALSA-2022:1759
AlmaLinux:8nbdkit-linuxdisk-plugin1.24.0-4.module_el8.6.0+2880+7d9e3703ALSA-2022:1759
AlmaLinux:8nbdkit-nbd-plugin1.24.0-4.module_el8.6.0+2880+7d9e3703ALSA-2022:1759
AlmaLinux:8nbdkit-python-plugin1.24.0-4.module_el8.6.0+2880+7d9e3703ALSA-2022:1759
AlmaLinux:8nbdkit-server1.24.0-4.module_el8.6.0+2880+7d9e3703ALSA-2022:1759
AlmaLinux:8nbdkit-ssh-plugin1.24.0-4.module_el8.6.0+2880+7d9e3703ALSA-2022:1759
AlmaLinux:8nbdkit-tar-filter1.24.0-4.module_el8.6.0+2880+7d9e3703ALSA-2022:1759
AlmaLinux:8nbdkit-tar-plugin1.24.0-4.module_el8.6.0+2880+7d9e3703ALSA-2022:1759
AlmaLinux:8nbdkit-tmpdisk-plugin1.24.0-4.module_el8.6.0+2880+7d9e3703ALSA-2022:1759
AlmaLinux:8nbdkit-vddk-plugin1.24.0-4.module_el8.6.0+2880+7d9e3703ALSA-2022:1759
AlmaLinux:8nbdkit-xz-filter1.24.0-4.module_el8.6.0+2880+7d9e3703ALSA-2022:1759
AlmaLinux:8netcf0.2.8-12.module_el8.6.0+2880+7d9e3703ALSA-2022:1759
AlmaLinux:8netcf-devel0.2.8-12.module_el8.6.0+2880+7d9e3703ALSA-2022:1759
AlmaLinux:8netcf-libs0.2.8-12.module_el8.6.0+2880+7d9e3703ALSA-2022:1759
AlmaLinux:8ocaml-hivex1.3.18-23.module_el8.6.0+2880+7d9e3703ALSA-2022:1759
AlmaLinux:8ocaml-hivex-devel1.3.18-23.module_el8.6.0+2880+7d9e3703ALSA-2022:1759
AlmaLinux:8ocaml-libguestfs1:1.44.0-5.module_el8.6.0+2880+7d9e3703.almaALSA-2022:1759
AlmaLinux:8ocaml-libguestfs-devel1:1.44.0-5.module_el8.6.0+2880+7d9e3703.almaALSA-2022:1759
AlmaLinux:8ocaml-libnbd1.6.0-5.module_el8.6.0+2880+7d9e3703ALSA-2022:1759
AlmaLinux:8ocaml-libnbd-devel1.6.0-5.module_el8.6.0+2880+7d9e3703ALSA-2022:1759
AlmaLinux:8perl-Sys-Guestfs1:1.44.0-5.module_el8.6.0+2880+7d9e3703.almaALSA-2022:1759
AlmaLinux:8perl-Sys-Virt8.0.0-1.module_el8.6.0+2880+7d9e3703ALSA-2022:1759
AlmaLinux:8perl-hivex1.3.18-23.module_el8.6.0+2880+7d9e3703ALSA-2022:1759
AlmaLinux:8python3-hivex1.3.18-23.module_el8.6.0+2880+7d9e3703ALSA-2022:1759
AlmaLinux:8python3-libguestfs1:1.44.0-5.module_el8.6.0+2880+7d9e3703.almaALSA-2022:1759
AlmaLinux:8python3-libnbd1.6.0-5.module_el8.6.0+2880+7d9e3703ALSA-2022:1759
AlmaLinux:8python3-libvirt8.0.0-1.module_el8.6.0+2880+7d9e3703ALSA-2022:1759
AlmaLinux:8qemu-guest-agent15:6.2.0-11.module_el8.6.0+2880+7d9e3703ALSA-2022:1759
AlmaLinux:8qemu-img15:6.2.0-11.module_el8.6.0+2880+7d9e3703ALSA-2022:1759
AlmaLinux:8qemu-kvm15:6.2.0-11.module_el8.6.0+2880+7d9e3703ALSA-2022:1759
AlmaLinux:8qemu-kvm-block-curl15:6.2.0-11.module_el8.6.0+2880+7d9e3703ALSA-2022:1759
AlmaLinux:8qemu-kvm-block-gluster15:6.2.0-11.module_el8.6.0+2880+7d9e3703ALSA-2022:1759
AlmaLinux:8qemu-kvm-block-iscsi15:6.2.0-11.module_el8.6.0+2880+7d9e3703ALSA-2022:1759
AlmaLinux:8qemu-kvm-block-rbd15:6.2.0-11.module_el8.6.0+2880+7d9e3703ALSA-2022:1759
AlmaLinux:8qemu-kvm-block-ssh15:6.2.0-11.module_el8.6.0+2880+7d9e3703ALSA-2022:1759
AlmaLinux:8qemu-kvm-common15:6.2.0-11.module_el8.6.0+2880+7d9e3703ALSA-2022:1759
AlmaLinux:8qemu-kvm-core15:6.2.0-11.module_el8.6.0+2880+7d9e3703ALSA-2022:1759
AlmaLinux:8qemu-kvm-docs15:6.2.0-11.module_el8.6.0+2880+7d9e3703ALSA-2022:1759
AlmaLinux:8qemu-kvm-hw-usbredir15:6.2.0-11.module_el8.6.0+2880+7d9e3703ALSA-2022:1759
AlmaLinux:8qemu-kvm-tests15:6.2.0-11.module_el8.6.0+2880+7d9e3703ALSA-2022:1759
AlmaLinux:8qemu-kvm-ui-opengl15:6.2.0-11.module_el8.6.0+2880+7d9e3703ALSA-2022:1759
AlmaLinux:8qemu-kvm-ui-spice15:6.2.0-11.module_el8.6.0+2880+7d9e3703ALSA-2022:1759
AlmaLinux:8ruby-hivex1.3.18-23.module_el8.6.0+2880+7d9e3703ALSA-2022:1759
AlmaLinux:8ruby-libguestfs1:1.44.0-5.module_el8.6.0+2880+7d9e3703.almaALSA-2022:1759
AlmaLinux:8seabios1.15.0-2.module_el8.6.0+2880+7d9e3703ALSA-2022:1759
AlmaLinux:8seabios-bin1.15.0-2.module_el8.6.0+2880+7d9e3703ALSA-2022:1759
AlmaLinux:8seavgabios-bin1.15.0-2.module_el8.6.0+2880+7d9e3703ALSA-2022:1759
AlmaLinux:8sgabios1:0.20170427git-3.module_el8.6.0+2880+7d9e3703ALSA-2022:1759
AlmaLinux:8sgabios-bin1:0.20170427git-3.module_el8.6.0+2880+7d9e3703ALSA-2022:1759
AlmaLinux:8supermin5.2.1-1.module_el8.6.0+2880+7d9e3703ALSA-2022:1759
AlmaLinux:8supermin-devel5.2.1-1.module_el8.6.0+2880+7d9e3703ALSA-2022:1759
AlmaLinux:8swtpm0.7.0-1.20211109gitb79fd91.module_el8.6.0+2880+7d9e3703ALSA-2022:1759
AlmaLinux:8swtpm-devel0.7.0-1.20211109gitb79fd91.module_el8.6.0+2880+7d9e3703ALSA-2022:1759
AlmaLinux:8swtpm-libs0.7.0-1.20211109gitb79fd91.module_el8.6.0+2880+7d9e3703ALSA-2022:1759
AlmaLinux:8swtpm-tools0.7.0-1.20211109gitb79fd91.module_el8.6.0+2880+7d9e3703ALSA-2022:1759
AlmaLinux:8swtpm-tools-pkcs110.7.0-1.20211109gitb79fd91.module_el8.6.0+2880+7d9e3703ALSA-2022:1759
AlmaLinux:8virt-dib1:1.44.0-5.module_el8.6.0+2880+7d9e3703.almaALSA-2022:1759
AlmaLinux:8virt-v2v1:1.42.0-18.module_el8.6.0+2880+7d9e3703ALSA-2022:1759
AlmaLinux:8virt-v2v-bash-completion1:1.42.0-18.module_el8.6.0+2880+7d9e3703ALSA-2022:1759
AlmaLinux:8virt-v2v-man-pages-ja1:1.42.0-18.module_el8.6.0+2880+7d9e3703ALSA-2022:1759
AlmaLinux:8virt-v2v-man-pages-uk1:1.42.0-18.module_el8.6.0+2880+7d9e3703ALSA-2022:1759
Debian:12qemu1:6.2+dfsg-1DEBIAN-CVE-2021-20196
Debian:13qemu1:6.2+dfsg-1DEBIAN-CVE-2021-20196
Debian:14qemu1:6.2+dfsg-1DEBIAN-CVE-2021-20196
Rocky Linux:8hivex0:1.3.18-23.module+el8.7.0+1084+97b81f61RLSA-2022:1759
Rocky Linux:8hivex0:1.3.18-23.module+el8.6.0+847+b490afddRLSA-2022:1759
Rocky Linux:8libguestfs1:1.44.0-5.module+el8.6.0+1052+ff61d164.rockyRLSA-2022:1759
Rocky Linux:8libguestfs-winsupport0:8.6-1.module+el8.7.0+1084+97b81f61RLSA-2022:1759
Rocky Linux:8libguestfs-winsupport0:8.6-1.module+el8.6.0+847+b490afddRLSA-2022:1759
Rocky Linux:8libiscsi0:1.18.0-8.module+el8.7.0+1084+97b81f61RLSA-2022:1759
Rocky Linux:8libiscsi0:1.18.0-8.module+el8.4.0+534+4680a14eRLSA-2022:1759
Rocky Linux:8libiscsi0:1.18.0-8.module+el8.6.0+847+b490afddRLSA-2022:1759
Rocky Linux:8libnbd0:1.6.0-5.module+el8.7.0+1084+97b81f61RLSA-2022:1759
Rocky Linux:8libnbd0:1.6.0-5.module+el8.6.0+847+b490afddRLSA-2022:1759
Rocky Linux:8libtpms0:0.9.1-0.20211126git1ff6fe1f43.module+el8.6.0+1052+ff61d164RLSA-2022:1759
Rocky Linux:8libvirt0:8.0.0-5.module+el8.6.0+847+b490afddRLSA-2022:1759
Rocky Linux:8libvirt-dbus0:1.3.0-2.module+el8.6.0+847+b490afddRLSA-2022:1759
Rocky Linux:8libvirt-dbus0:1.3.0-2.module+el8.4.0+534+4680a14eRLSA-2022:1759
Rocky Linux:8libvirt-dbus0:1.3.0-2.module+el8.7.0+1084+97b81f61RLSA-2022:1759
Rocky Linux:8libvirt-python0:8.0.0-1.module+el8.6.0+847+b490afddRLSA-2022:1759
Rocky Linux:8nbdkit0:1.24.0-4.module+el8.6.0+847+b490afddRLSA-2022:1759
Rocky Linux:8netcf0:0.2.8-12.module+el8.4.0+534+4680a14eRLSA-2022:1759
Rocky Linux:8netcf0:0.2.8-12.module+el8.7.0+1084+97b81f61RLSA-2022:1759
Rocky Linux:8netcf0:0.2.8-12.module+el8.6.0+847+b490afddRLSA-2022:1759
Rocky Linux:8perl-Sys-Virt0:8.0.0-1.module+el8.7.0+1084+97b81f61RLSA-2022:1759
Rocky Linux:8perl-Sys-Virt0:8.0.0-1.module+el8.6.0+847+b490afddRLSA-2022:1759
Rocky Linux:8qemu-kvm5:6.2.0-11.module+el8.6.0+1000+18e3b59f.5RLSA-2022:1759
Rocky Linux:8seabios0:1.15.0-2.module+el8.6.0+1052+ff61d164RLSA-2022:1759
Rocky Linux:8sgabios1:0.20170427git-3.module+el8.6.0+847+b490afddRLSA-2022:1759
Rocky Linux:8sgabios1:0.20170427git-3.module+el8.4.0+534+4680a14eRLSA-2022:1759
Rocky Linux:8sgabios1:0.20170427git-3.module+el8.7.0+1084+97b81f61RLSA-2022:1759
Rocky Linux:8supermin0:5.2.1-1.module+el8.6.0+1052+ff61d164RLSA-2022:1759
Rocky Linux:8swtpm0:0.7.0-1.20211109gitb79fd91.module+el8.6.0+847+b490afddRLSA-2022:1759
Rocky Linux:8virt-v2v1:1.42.0-18.module+el8.6.0+847+b490afddRLSA-2022:1759
Ubuntu:22.04:LTSqemu1:6.2+dfsg-2ubuntu5UBUNTU-CVE-2021-20196
Ubuntu:22.04:LTSxenno fix listedUBUNTU-CVE-2021-20196
Ubuntu:24.04:LTSxenno fix listedUBUNTU-CVE-2021-20196
Ubuntu:25.10xenno fix listedUBUNTU-CVE-2021-20196
Ubuntu:26.04:LTSxenno fix listedUBUNTU-CVE-2021-20196
Ubuntu:26.10xenno fix listedUBUNTU-CVE-2021-20196

Affected products (as reported)

VendorProductVersions
n/a qemu vulnerable up to (including) qemu 5.2.0

Weakness: CWE-476

References