BitchX IRC clients, versions 75 up to and including 1.0c16, are vulnerable to a Denial of Service and possible remote execution of code. By /invite-ing someone to a channel name containing formatting characters (%s, %n, etc) an IRC user can cause the targetted user's BitchX client to seg-fault. This is caused by the fact that bitchx passes the channel name from the invite into the logging function as its format string [which is used directly in a vsprintf], rather than as an argument to the format. This also affects the KILL command.