Mesop is a Python-based UI framework designed for rapid web apps development. A vulnerability has been discovered and fixed in Mesop that could potentially allow unauthorized access to files on the server hosting the Mesop application. The vulnerability was related to insufficient input validation in a specific endpoint. This could have allowed an attacker to access files not intended to be served. Users are strongly advised to update to the latest version of Mesop immediately. The latest version includes a fix for this vulnerability. At time of publication 0.12.4 is the most recently available version of Mesop.