USN-8104-1: Flask vulnerability

Publication date

18 March 2026

Overview

Flask could be made to expose sensitive information over the network.


Packages

  • flask - Micro web framework based on Werkzeug and Jinja2

Details

Shourya Jaiswal discovered that Flask did not correctly mark certain web
responses as user-specific. A remote attacker could possibly use this
issue to obtain sensitive information.

Shourya Jaiswal discovered that Flask did not correctly mark certain web
responses as user-specific. A remote attacker could possibly use this
issue to obtain sensitive information.

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 python3-flask –  3.0.2-1ubuntu1.1
22.04 LTS jammy python3-flask –  2.0.1-2ubuntu1.2
20.04 LTS focal python3-flask –  1.1.1-2ubuntu0.1+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.


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