imageZMQ transfers OpenCV images using ZMQ and TCP. It opens ports on both the the sending and receiving computers. imageZMQ does not have any explicit checks on the security of the TCP connection or the ports it uses. Firewalls and port security need to be handled in the programs(s) using imageZMQ. Code accordingly.
If you believe you have discovered a security vulnerability (or any other bug) in imageZMQ, open an issue and let's discuss it.