changedetection.io is a free open source web page change detection tool. In versions prior to 0.53.2, the /static/<group>/<filename> route accepts group="..", which causes send_from_directory("static/..", filename) to execute. This moves the base directory up to /app/changedetectionio, enabling unauthenticated local file read of application source files (e.g., flask_app.py). Version 0.53.2 fixes the issue.