CVE-2021-20196

QEMU: block: fdc: null pointer dereference may lead to guest crash

Severity Score

6.5

*CVSS v3.1

Exploit Likelihood

*EPSS

Affected Versions

*CPE

Public Exploits

*Multiple Sources

Exploited in Wild

*KEV

Decision

*SSVC

Descriptions

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.

Se encontró un fallo de desreferencia de puntero NULL en el emulador floppy disk de QEMU. Este problema ocurre mientras se procesan comandos de ioport de lectura y escritura si la unidad de disquete seleccionada no es inicializada con un dispositivo de bloque. Este fallo permite a un usuario invitado privilegiado bloquear el proceso QEMU en el host, resultando en una denegación de servicio. La mayor amenaza de esta vulnerabilidad es la disponibilidad del sistema

*Credits: N/A

CVSS Scores

Attack Vector

Local

Attack Complexity

Low

Privileges Required

Low

User Interaction

None

Scope

Changed

Confidentiality

None

Integrity

None

Availability

High

Attack Vector

Local

Attack Complexity

Low

Privileges Required

High

User Interaction

None

Scope

Changed

Confidentiality

None

Integrity

None

Availability

Low

Attack Vector

Local

Attack Complexity

Low

Authentication

None

Confidentiality

None

Integrity

None

Availability

Partial

* Common Vulnerability Scoring System

SSVC

Decision:-

Exploitation

Automatable

Tech. Impact

* Organization's Worst-case Scenario

Timeline

2020-12-17 CVE Reserved
2021-05-26 CVE Published
2023-03-08 EPSS Updated
2024-08-03 CVE Updated
2024-08-03 First Exploit
---------- Exploited in Wild
---------- KEV Due Date

CWE

CWE-476: NULL Pointer Dereference

CAPEC

References (7)

URL	Tag	Source
https://lists.debian.org/debian-lts-announce/2022/04/msg00002.html	Mailing List
https://lists.debian.org/debian-lts-announce/2022/09/msg00008.html	Mailing List
https://security.netapp.com/advisory/ntap-20210708-0004	Third Party Advisory

URL	Date	SRC
https://bugs.launchpad.net/qemu/+bug/1912780	2024-08-03

URL	Date	SRC
https://www.openwall.com/lists/oss-security/2021/01/28/1	2023-02-12

URL	Date	SRC
https://access.redhat.com/security/cve/CVE-2021-20196	2022-05-10
https://bugzilla.redhat.com/show_bug.cgi?id=1919210	2022-05-10

Affected Vendors, Products, and Versions

Vendor		Product				Version		Other		Status
Vendor	Product	Version	Other	Status	<-- -->	Vendor	Product	Version	Other	Status
Qemu Search vendor "Qemu"		Qemu Search vendor "Qemu" for product "Qemu"				5.2.0 Search vendor "Qemu" for product "Qemu" and version "5.2.0"		-		Affected
Debian Search vendor "Debian"		Debian Linux Search vendor "Debian" for product "Debian Linux"				9.0 Search vendor "Debian" for product "Debian Linux" and version "9.0"		-		Affected
Debian Search vendor "Debian"		Debian Linux Search vendor "Debian" for product "Debian Linux"				10.0 Search vendor "Debian" for product "Debian Linux" and version "10.0"		-		Affected