Flask Vulnerability Exposes Sensitive Information in Ubuntu Releases

A security vulnerability identified as CVE-2026-27205 affects Flask, a micro web framework used in Ubuntu 24.04 LTS, 22.04 LTS, and 20.04 LTS. Discovered by Shourya Jaiswal, the issue arises from Flask's failure to mark certain web responses as user-specific, potentially allowing remote attackers to access sensitive information over the network. The affected versions include python3-flask 3.0.2-1ubuntu1.1 for Ubuntu 24.04 LTS, python3-flask 2.0.1-2ubuntu1.2 for Ubuntu 22.04 LTS, and python3-flask 1.1.1-2ubuntu0.1+esm1 for Ubuntu 20.04 LTS. Users are advised to perform a standard system update to mitigate the risk. The vulnerability was published on February 21, 2026, and has been addressed with available patches. The issue highlights the importance of timely updates to prevent potential data exposure.

Key Points: • CVE-2026-27205 affects multiple Ubuntu LTS releases due to Flask vulnerability. • Flask's failure to mark web responses as user-specific could lead to sensitive data exposure. • Users should update to the latest python3-flask versions to mitigate the vulnerability.