Tautulli is a Python based monitoring and tracking tool for Plex Media Server. In Tautulli v2.15.3 and earlier, an attacker with administrative access can use the pms_image_proxy endpoint to write arbitrary python scripts into the application filesystem. This leads to remote code execution when combined with the Script notification agent. If an attacker with administrative access changes the URL of the PMS to a server they control, they can then abuse the pms_image_proxy to obtain a file write into the application filesystem. This can be done by making a pms_image_proxy request with a URL in the img parameter and the desired file name in the img_format parameter. Tautulli then uses a hash of the desired metadata together with the img_format in order to construct a file path. Since the…