We've released updates to matrix-appservice-irc and our forked node-irc that it depends on to patch a High security vulnerability. It's advised to update to 0.34.0 as soon as possible.
The vulnerability allows an attacker to manipulate a Matrix user into executing IRC commands by having them reply to a maliciously crafted message.
Incorrect handling of a CR character allowed for making part of the message be sent to the IRC server verbatim rather than as a message to the channel.
If you are currently a matrix-appservice-irc user, exercise caution when replying to messages from untrusted participants in IRC bridged rooms until your bridge instance has been upgraded.
The vulnerability has been patched in node-irc version 1.2.1 and matrix-appservice-irc 0.34.0. You can get the release on Github.
The bridges running on the Libera Chat, OFTC and other networks bridged by the Matrix.org Foundation have been patched.
Thank you, Val Lorentz for reporting this vulnerability.