Multiple buffer overflows in BitchX IRC client 1.0-0c19 and earlier allow remote malicious IRC servers to cause a denial of service (crash) and possibly execute arbitrary code via long hostnames, nicknames, or channel names, which are not properly handled by the functions (1) send_ctcp, (2) cannot_join_channel, (3) cluster, (4) BX_compress_modes, (5) handle_oper_vision, and (6) ban_it.