The IRC protocol plugin in Gaim 1.2.0 and possibly earlier versions allows (1) remote attackers to inject arbitrary Gaim markup via irc_msg_kick irc_msg_mode irc_msg_part irc_msg_quit (2) remote attackers to inject arbitrary Pango markup and pop up empty dialog boxes via irc_msg_invite or (3) malicious IRC servers to cause a denial of service (application crash) by injecting certain Pango markup into irc_msg_badmode irc_msg_banned irc_msg_unknown irc_msg_nochan functions.