CVE-2026-21218

Publication date 10 February 2026

Last updated 16 February 2026

Ubuntu priority

Medium

Why this priority?

Cvss 3 Severity Score

7.5 · High

Score breakdown

Description

Improper handling of missing special element in .NET allows an unauthorized attacker to perform spoofing over a network.

Read the notes from the security team

Status

Package Ubuntu Release Status
dotnet6 25.10 questing Not in release
25.04 plucky Not in release
24.04 LTS noble Not in release
22.04 LTS jammy
Vulnerable, fix deferred
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
dotnet7 25.10 questing Not in release
25.04 plucky Not in release
24.04 LTS noble Not in release
22.04 LTS jammy Ignored see notes
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
dotnet8 25.10 questing
Fixed 8.0.124-8.0.24-0ubuntu1~25.10.1
24.04 LTS noble
Fixed 8.0.124-8.0.24-0ubuntu1~24.04.1
22.04 LTS jammy
Fixed 8.0.124-8.0.24-0ubuntu1~22.04.1
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
dotnet9 25.10 questing
Fixed 9.0.114-9.0.13-0ubuntu1~25.10.1
24.04 LTS noble Not in release
22.04 LTS jammy 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
dotnet10 25.10 questing
Fixed 10.0.103-10.0.3-0ubuntu1~25.10.1
24.04 LTS noble
Fixed 10.0.103-10.0.3-0ubuntu1~24.04.1
22.04 LTS jammy 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

Notes

iconstantin

.NET 7 is end of life upstream.

mdeslaur

Marking .NET 6 as deferred until information is available to determine if it is impacted.

Severity score breakdown

Parameter Value
Base score 7.5 · High
Attack vector Network
Attack complexity Low
Privileges required None
User interaction None
Scope Unchanged
Confidentiality None
Integrity impact High
Availability impact None
Vector CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N

References

Related Ubuntu Security Notices (USN)

Other references