Opera 6.0.3, when using Squid 2.4 for HTTPS proxying, does not properly handle when accepting a non-global certificate authority (CA) certificate from a site and establishing a subsequent HTTPS connection, which allows remote attackers to cause a denial of service (crash).
https://euvd.enisa.europa.eu/vulnerability/EUVD-2002-2392
http://www.securityfocus.com/bid/6218