The Eclipse Hono AMQP and MQTT protocol adapters do not check whether an authenticated gateway device is authorized to receive command & control messages when it has subscribed only to commands for a specific device. The missing check involves verifying that the command target device is configured giving permission for the gateway device to act on its behalf. This means an authenticated device of a certain tenant, notably also a non-gateway device acting like a gateway, may receive command & control messages targeted at a different device of the same tenant without corresponding permissions getting checked.

In Eclipse Hono version 1.3.0 and 1.4.0 the AMQP protocol adapter does not verify the size of AMQP messages received from devices. In particular, a device may send messages that are bigger than the max-message-size that the protocol adapter has indicated during link establishment. While the AMQP 1.0 protocol explicitly disallows a peer to send such messages, a hand crafted AMQP 1.0 client could exploit this behavior in order to send a message of unlimited size to the adapter, eventually causing the adapter to fail with an out of memory exception.