USN-8144-1: Undertow vulnerability

Publication date

2 April 2026

Overview

Undertow would allow unintended access to user sessions over the network.


Packages

  • undertow - Java web server based on non-blocking IO

Details

It was discovered that Undertow incorrectly validated the Host header in
incoming HTTP requests. A remote attacker could possibly use this issue
to gain unintended access to user sessions.

It was discovered that Undertow incorrectly validated the Host header in
incoming HTTP requests. A remote attacker could possibly use this issue
to gain unintended access to user sessions.

Update instructions

In general, a standard system update will make all the necessary changes.

Learn more about how to get the fixes.

The problem can be corrected by updating your system to the following package versions:

Ubuntu Release Package Version
24.04 LTS noble libundertow-java –  2.3.8-2ubuntu0.1~esm1  
22.04 LTS jammy libundertow-java –  2.2.16-1ubuntu0.1~esm1  
20.04 LTS focal libundertow-java –  2.0.29-1ubuntu0.1~esm1  
18.04 LTS bionic libundertow-java –  1.4.23-3ubuntu0.1~esm1  
16.04 LTS xenial libundertow-java –  1.3.16-1ubuntu0.1~esm1  

Reduce your security exposure

Ubuntu Pro provides ten-year security coverage to 25,000+ packages in Main and Universe repositories, and it is free for up to five machines.


Have additional questions?

Talk to a member of the team ›