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

Summary

mEye contains 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.

Details

The issue exists in the media playback and download functionality.

The filename parameter is passed to mediafiles.get_media_path():

def get_media_path(camera_config, path, media_type):
    target_dir = camera_config.get('target_dir')
    full_path = os.path.join(target_dir, path)
    return full_path

When path is an absolute path (e.g. /etc/motioneye/motion.conf), Python's os.path.join() discards target_dir entirely and returns the absolute path as-is. This would normally be caught by Tornado's StaticFileHandler path validation, but MoviePlaybackHandler explicitly overrides both safety checks (movie_playback.py lines 111-115):

def get_absolute_path(self, root, path):
    return path

def validate_absolute_path(self, root, absolute_path):
    return absolute_path

This allows reading any file on the filesystem that the motionEye process can access.

The same path traversal exists in the movie download, picture download, and picture preview handlers:

• GET /movie/<camera_id>/download/
• GET /picture/<camera_id>/download/
• GET /picture/<camera_id>/preview/

# PoC

GET /movie/1/playback//etc/motioneye/motion.conf HTTP/1.1
Host: target:8765

# Fix

Do not allow absolute paths supplied by user input.

Validate that the fully resolved canonical path remains within the configured camera media directory before serving a file.

Additionally, Tornado’s built-in path validation should not be bypassed unless equivalent validation is performed by motionEye.