CVE-2021-3713

Publication date 25 August 2021

Last updated 25 August 2025

Ubuntu priority

Cvss 3 Severity Score

Description

An out-of-bounds write flaw was found in the UAS (USB Attached SCSI) device emulation of QEMU in versions prior to 6.2.0-rc0. The device uses the guest supplied stream number unchecked, which can lead to out-of-bounds access to the UASDevice->data3 and UASDevice->status3 fields. A malicious guest user could use this flaw to crash QEMU or potentially achieve code execution with the privileges of the QEMU process on the host.

Read the notes from the security team

Status

Show unmaintained releases

Package	Ubuntu Release	Status
qemu	22.04 LTS jammy	Fixed 1:6.2+dfsg-2ubuntu5
	21.10 impish	Fixed 1:6.0+dfsg-2expubuntu1.2
	21.04 hirsute	Ignored end of life
	20.04 LTS focal	Not affected
	18.04 LTS bionic	Not affected
	16.04 LTS xenial	Not affected
	14.04 LTS trusty	Not affected

Notes

sbeattie

Red Hat claims UAS (usb attached scsi) device emulation is not supported by libvirt

mdeslaur

introduced in 1.5.0

Patch details

For informational purposes only. We recommend not to cherry-pick updates. How can I get the fixes?

Package	Patch details
qemu	Upstream: https://git.qemu.org/?p=qemu.git;a=commit;h=13b250b12ad3c59114a6a17d59caf073ce45b33a

Severity score breakdown

CVSS version: CVSS v3.0

Base score 7.4 · High

Base metrics

Parameter	Value
Attack vector	Physical
Attack complexity	Low
Privileges required	Low
User interaction	None
Scope	Changed
Confidentiality impact	High
Integrity impact	High
Availability impact	High

Scores

Parameter	Value
Base score	7.4 · High
Exploitability score	-
Impact score	-