The PluginContext object of Opera 6.05 and 7.0 allows remote attackers to cause a denial of service (crash) via an HTTP request containing a long string that gets passed to the ShowDocument method.
https://exchange.xforce.ibmcloud.com/vulnerabilities/11280
https://euvd.enisa.europa.eu/vulnerability/EUVD-2003-1387
http://www.securityfocus.com/bid/6814