Ubuntu Security Notices USN-8104-1 USN-8104-1: Flask vulnerability Publication date 18 March 2026 Overview Flask could be made to expose sensitive information over the network. Releases 24.04 LTS 22.04 LTS 20.04 LTS Open side navigation Close side navigation Packages Details Update instructions References 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 Ubuntu Pro Fix available with Ubuntu Pro . 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. Get Ubuntu Pro References CVE-2026-27205 CVE-2026-27205