motionEye's Absolute Path Traversal in Media File Handlers Allows Arbitrary File Read

motionEye (mEye) is an online interface for a piece of software called "motion," which is a video surveillance program with motion detection. Versions prior to 0.44.0 contain an absolute path traversal vulnerability in multiple media file handlers that allows an attacker to read arbitrary files from the filesystem. The affected handlers accept a user-controlled filename parameter and construct filesystem paths using `os.path.join()`. When an absolute path is supplied, Python discards the configured media directory and returns the attacker-supplied path directly. The application then bypasses Tornado's built-in path validation by overriding the relevant safety checks. As a result, an attacker can access files outside of the configured camera media directory, subject to the permissions of the motionEye process. Version 0.44.0 fixes the issue.