The broker in Eclipse Mosquitto 1.3.2 through 2.x before 2.0.16 has a memory leak that can be abused remotely when a client sends many QoS 2 messages with duplicate message IDs, and fails to respond to PUBREC commands. This occurs because of mishandling of EAGAIN from the libc send function.
In Mosquitto before 2.0.16, excessive memory is allocated based on malicious initial packets that are not CONNECT packets.
In Mosquitto before 2.0.16, a memory leak occurs when clients send v5 CONNECT packets with a will message that contains invalid property types.
Please stabilize >2.0.16.