CVE-2021-20257

Publication date 23 February 2021

Last updated 18 August 2025

Ubuntu priority

Medium

Why this priority?

Cvss 3 Severity Score

6.5 · Medium

Score breakdown

Description

An infinite loop flaw was found in the e1000 NIC emulator of the QEMU. This issue occurs while processing transmits (tx) descriptors in process_tx_desc if various descriptor fields are initialized with invalid values. This flaw allows a guest to consume CPU cycles on the host, resulting in a denial of service. The highest threat from this vulnerability is to system availability.

Status

Package Ubuntu Release Status
qemu 25.10 questing
Not affected
25.04 plucky
Not affected
24.10 oracular
Not affected
24.04 LTS noble
Not affected
23.10 mantic
Not affected
23.04 lunar
Not affected
22.10 kinetic
Not affected
22.04 LTS jammy
Not affected
21.10 impish
Not affected
21.04 hirsute
Not affected
20.10 groovy
Fixed 1:5.0-5ubuntu9.9
20.04 LTS focal
Fixed 1:4.2-3ubuntu6.17
18.04 LTS bionic
Fixed 1:2.11+dfsg-1ubuntu7.37
16.04 LTS xenial
Vulnerable
14.04 LTS trusty
Vulnerable
qemu-kvm 25.10 questing Not in release
25.04 plucky Not in release
24.10 oracular Not in release
24.04 LTS noble Not in release
23.10 mantic Not in release
23.04 lunar Not in release
22.10 kinetic Not in release
22.04 LTS jammy Not in release
21.10 impish Not in release
21.04 hirsute Not in release
20.10 groovy Not in release
20.04 LTS focal Not in release
18.04 LTS bionic Not in release
16.04 LTS xenial Not in release
14.04 LTS trusty Not in release

Patch details

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

Package Patch details
qemu

Severity score breakdown

Parameter Value
Base score 6.5 · Medium
Attack vector Local
Attack complexity Low
Privileges required Low
User interaction None
Scope Changed
Confidentiality None
Integrity impact None
Availability impact High
Vector CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:N/I:N/A:H

References

Related Ubuntu Security Notices (USN)

Other references