Buffer overflow in Netscape 6 and Mozilla 1.0 RC1 and earlier allows remote attackers to cause a denial of service (crash) and possibly execute arbitrary code via a long channel name in an IRC URI.
http://www.iss.net/security_center/static/8976.php
http://secunia.com/advisories/8039
http://online.securityfocus.com/archive/1/270249
http://distro.conectiva.com.br/atualizacoes/?id=a&anuncio=000490