CVE-2021-4145

Publication date 25 January 2022

Last updated 25 August 2025

Ubuntu priority

Cvss 3 Severity Score

Description

A NULL pointer dereference issue was found in the block mirror layer of QEMU in versions prior to 6.2.0. The `self` pointer is dereferenced in mirror_wait_on_conflicts() without ensuring that it's not NULL. A malicious unprivileged user within the guest could use this flaw to crash the QEMU process on the host when writing data reaches the threshold of mirroring node.

Read the notes from the security team

Status

Show unmaintained releases

Package	Ubuntu Release	Status
qemu	22.04 LTS jammy	Not affected
	21.10 impish	Not affected
	21.04 hirsute	Not affected
	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

mdeslaur

introduced in 6.1.0

Patch details

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

Package	Patch details
qemu	Upstream: 66fed30

Severity score breakdown

CVSS version: CVSS v3.0

Base score 6.5 · Medium

Base metrics

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

Scores

Parameter	Value
Base score	6.5 · Medium
Exploitability score	-
Impact score	-

Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:N/I:N/A:H

References

Other references

https://www.cve.org/CVERecord?id=CVE-2021-4145