Multiple buffer overflows in the IRC component of Trillian 0.73 and 0.74 allows remote malicious IRC servers to cause a denial of service and possibly execute arbitrary code via (1) a large response from the server, (2) a JOIN with a long channel name, (3) a long "raw 221" message, (4) a PRIVMSG with a long nickname, or (5) a long response from an IDENT server.