Matrix IRC Bridge allows IRC command injection to own puppeted user

matrix-appservice-irc is a Node.js IRC bridge for Matrix. The matrix-appservice-irc bridge up to version 3.0.3 contains a vulnerability which can lead to arbitrary IRC command execution as the puppeted user. The attacker can only inject commands executed as their own IRC user. The vulnerability has been patched in matrix-appservice-irc version 3.0.4.