The Microsoft Java implementation, as used in Internet Explorer, allows remote attackers to cause a denial of service (crash) and possibly conduct other unauthorized activities via applet tags in HTML that bypass Java class restrictions (such as private constructors) by providing the class name in the code parameter, aka "Incomplete Java Object Instantiation Vulnerability."
https://docs.microsoft.com/en-us/security-updates/securitybulletins/2002/ms02-069
http://www.securityfocus.com/bid/6136
http://www.iss.net/security_center/static/10588.php