CVE-2024-32000: Matrix IRC Bridge truncated content of messages can be leaked

The matrix-appservice-irc before version 2.0.0 can be exploited to leak the truncated body of a message if a malicious user sends a Matrix reply to an event ID they don’t have access to. As a precondition to the attack, the malicious user needs to know the event ID of the message they want to leak, as well as to be joined to both the Matrix room and the IRC channel it is bridged to.

The message reply containing the leaked message content is visible to IRC channel members when this happens.