Mosquitto 1.6.12 and 1.5.10 have been released.


  • In some circumstances, Mosquitto could leak memory when handling PUBLISH messages. This is limited to incoming QoS 2 messages, and is related to the combination of the broker having persistence enabled, a clean session=false client, which was connected prior to the broker restarting, then has reconnected and has now sent messages at a sufficiently high rate that the incoming queue at the broker has filled up and hence messages are being dropped. This is more likely to have an effect where max_queued_messages is a small value. This has now been fixed. Closes #1793.

The following fixes apply to 1.6.12 only.


  • Build warning fixes when building with WITH_BRIDGE=no and WITH_TLS=no.


  • All clients exit with an error exit code on CONNACK failure. Closes #1778.
  • Don't busy loop with mosquitto_pub -l on a slow connection.