The Journey of Bypassing Ubuntu’s Unprivileged Namespace Restriction

Pumpkin

2025-06-26

Recently, Ubuntu introduced sandbox mechanisms to reduce the attack surface, and they seemed unbreakable. However, after carrying out in-depth research, we found that the implementation contained some issues, and bypassing it was not as difficult as expected. This post will explain how we began our research at the kernel level and discovered a bypass method. We will also share some interesting stories from the process.