psyBNC 2.3 allows remote attackers to cause a denial of service (CPU consumption and resource exhaustion) by sending a PASS command with a long password argument and quickly killing the connection, which is not properly terminated by psyBNC.
http://www.iss.net/security_center/static/8912.php
http://online.securityfocus.com/archive/1/269131
http://archives.neohapsis.com/archives/bugtraq/2002-04/0322.html