CVE-2021-20196
published 2021-05-26CVE-2021-20196: 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…
PriorityP425medium6.5CVSS 3.1
AVLACLPRLUINSCCNINAH
EPSS
0.47%
38.4th percentile
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
12 ranges
| Vendor | Product | Version range | Fixed in |
|---|---|---|---|
| debian | debian_linux | — | — |
| debian | debian_linux | — | — |
| debian | qemu | < qemu 1:6.2+dfsg-1 (bookworm) | qemu 1:6.2+dfsg-1 (bookworm) |
| qemu | qemu | — | — |
| qemu | qemu | — | — |
| qemu | qemu | >= 0 < 1:5.2+dfsg-11+deb11u3 | 1:5.2+dfsg-11+deb11u3 |
| qemu | qemu | >= 0 < 1:6.2+dfsg-1 | 1:6.2+dfsg-1 |
| qemu | qemu | >= 0 < 1:6.2+dfsg-1 | 1:6.2+dfsg-1 |
| qemu | qemu | >= 0 < 1:6.2+dfsg-1 | 1:6.2+dfsg-1 |
| qemu | qemu | >= 0 < 1:2.11+dfsg-1ubuntu7.39 | 1:2.11+dfsg-1ubuntu7.39 |
| qemu | qemu | >= 0 < 1:4.2-3ubuntu6.21 | 1:4.2-3ubuntu6.21 |
| ubuntu | qemu | — | — |
CVSS provenance
nvdv3.16.5MEDIUMCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:N/I:N/A:H
nvdv2.02.1LOWAV:L/AC:L/Au:N/C:N/I:N/A:P
osv6.5MEDIUM
vendor_debian6.5MEDIUM
vendor_redhat6.5MEDIUM
vendor_ubuntu6.5MEDIUM
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Ubuntu
QEMU regression
vendor_ubuntu·2026-06-28·CVSS 3.8
CVE-2020-11947 [LOW] QEMU regression
Title: QEMU regression
Summary: USN-8412-1 introduced a regression in QEMU
USN-8412-1 fixed vulnerabilities QEMU. On Ubuntu 20.04 LTS, the fix for
CVE-2024-4467 was incomplete and prevented the creation of boot volumes
from qcow2 images. This update fixes the problem.
We apologize for the inconvenience.
Original advisory details:
Felipe Franciosi, Raphael Norwitz, and Peter Turschmid discovered that the
iSCSI block driver in QEMU incorrectly handled certain responses from an
iSCSI server. A remote attacker could possibly use this issue to cause
QEMU to crash, resulting in a denial of service, or possibly execute
arbitrary code. This issue only affected Ubuntu 14.04 LTS. (CVE-2020-1711)
It was discovered that the iSCSI block driver in QEMU incorrectly handled
certain memory operations
Ubuntu
QEMU vulnerabilities
vendor_ubuntu·2026-06-09·CVSS 3.8
CVE-2021-3416 [LOW] QEMU vulnerabilities
Title: QEMU vulnerabilities
Summary: Several security issues were fixed in QEMU.
Felipe Franciosi, Raphael Norwitz, and Peter Turschmid discovered that the
iSCSI block driver in QEMU incorrectly handled certain responses from an
iSCSI server. A remote attacker could possibly use this issue to cause QEMU
to crash, resulting in a denial of service, or possibly execute arbitrary
code. This issue only affected Ubuntu 14.04 LTS. (CVE-2020-1711)
It was discovered that the iSCSI block driver in QEMU incorrectly handled
certain memory operations, leading to a heap-based buffer over-read. An
attacker could possibly use this issue to expose sensitive information from
the host. This issue only affected Ubuntu 14.04 LTS. (CVE-2020-11947)
Ziming Zhang discovered that the SM501 display driver in QEM
Ubuntu
QEMU vulnerabilities
vendor_ubuntu·2022-02-28·CVSS 6.5
CVE-2021-3544 [MEDIUM] QEMU vulnerabilities
Title: QEMU vulnerabilities
Summary: Several security issues were fixed in QEMU.
Gaoning Pan discovered that QEMU incorrectly handled the floppy disk
emulator. An attacker inside the guest could use this issue to cause QEMU
to crash, resulting in a denial of service. (CVE-2021-20196)
Gaoning Pan discovered that the QEMU vmxnet3 NIC emulator incorrectly
handled certain values. An attacker inside the guest could use this issue
to cause QEMU to crash, resulting in a denial of service. (CVE-2021-20203)
It was discovered that the QEMU vhost-user GPU device contained several
security issues. An attacker inside the guest could use these issues to
cause QEMU to crash, resulting in a denial of service, leak sensitive
information, or possibly execute arbitrary code. This issue only affected
Ubun
Red Hat
QEMU: block: fdc: null pointer dereference may lead to guest crash
vendor_redhat·2021-01-23·CVSS 6.5
CVE-2021-20196 [MEDIUM] CWE-476 QEMU: block: fdc: null pointer dereference may lead to guest crash
QEMU: block: fdc: null pointer dereference may lead to guest crash
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.
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 t
Debian
CVE-2021-20196: qemu - A NULL pointer dereference flaw was found in the floppy disk emulator of QEMU. T...
vendor_debian·2021·CVSS 6.5
CVE-2021-20196 [MEDIUM] CVE-2021-20196: qemu - A NULL pointer dereference flaw was found in the floppy disk emulator of QEMU. T...
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.
Scope: local
bookworm: resolved (fixed in 1:6.2+dfsg-1)
bullseye: resolved (fixed in 1:5.2+dfsg-11+deb11u3)
forky: resolved (fixed in 1:6.2+dfsg-1)
sid: resolved (fixed in 1:6.2+dfsg-1)
trixie: resolved (fixed in 1:6.2+dfsg-1)
GHSA
GHSA-ggpp-fxg5-wp87: A NULL pointer dereference flaw was found in the floppy disk emulator of QEMU
ghsa_unreviewed·2022-05-24
CVE-2021-20196 [MEDIUM] CWE-476 GHSA-ggpp-fxg5-wp87: A NULL pointer dereference flaw was found in the floppy disk emulator of QEMU
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.
OSV
qemu vulnerabilities
osv·2022-02-28·CVSS 6.5
CVE-2021-20196 [MEDIUM] qemu vulnerabilities
qemu vulnerabilities
Gaoning Pan discovered that QEMU incorrectly handled the floppy disk
emulator. An attacker inside the guest could use this issue to cause QEMU
to crash, resulting in a denial of service. (CVE-2021-20196)
Gaoning Pan discovered that the QEMU vmxnet3 NIC emulator incorrectly
handled certain values. An attacker inside the guest could use this issue
to cause QEMU to crash, resulting in a denial of service. (CVE-2021-20203)
It was discovered that the QEMU vhost-user GPU device contained several
security issues. An attacker inside the guest could use these issues to
cause QEMU to crash, resulting in a denial of service, leak sensitive
information, or possibly execute arbitrary code. This issue only affected
Ubuntu 21.10. (CVE-2021-3544, CVE-2021-3545, CVE-2021-3546)
It w
OSV
CVE-2021-20196: A NULL pointer dereference flaw was found in the floppy disk emulator of QEMU
osv·2021-05-26·CVSS 6.5
CVE-2021-20196 [MEDIUM] CVE-2021-20196: A NULL pointer dereference flaw was found in the floppy disk emulator of QEMU
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.
No detection rules found.
No public exploits indexed.
No writeups or analysis indexed.
https://bugs.launchpad.net/qemu/+bug/1912780https://lists.debian.org/debian-lts-announce/2022/04/msg00002.htmlhttps://lists.debian.org/debian-lts-announce/2022/09/msg00008.htmlhttps://security.netapp.com/advisory/ntap-20210708-0004/https://www.openwall.com/lists/oss-security/2021/01/28/1https://bugs.launchpad.net/qemu/+bug/1912780https://lists.debian.org/debian-lts-announce/2022/04/msg00002.htmlhttps://lists.debian.org/debian-lts-announce/2022/09/msg00008.htmlhttps://security.netapp.com/advisory/ntap-20210708-0004/https://www.openwall.com/lists/oss-security/2021/01/28/1
2021-05-26
Published