Apache Guacamole 1.3.0 and older may incorrectly include a private tunnel identifier in the non-private details of some REST responses. This may allow an authenticated user who already has permission to access a particular connection to read from or interact with another user's active use of that same connection.
https://lists.apache.org/thread/5l31k4jmzdsfz0xt8osrbl878gb3b7ro