Spotipy's cache file, containing spotify auth token, is created with overly broad permissions
The CacheHandler class creates a cache file to store the auth token here: https://github.com/spotipy-dev/spotipy/blob/master/spotipy/cache_handler.py#L93-L98 The file created has rw-r–r– (644) permissions by default, when it could be locked down to rw——- (600) permissions. I think 600 is a sensible default.