Multiple unspecified vulnerabilities in Opera before 10.54 have unknown impact and attack vectors related to (1) "extremely severe," (2) "highly severe," (3) "moderately severe," and (4) "less severe" issues.
https://oval.cisecurity.org/repository/search/definition/oval%3Aorg.mitre.oval%3Adef%3A11352
http://www.vupen.com/english/advisories/2010/1529
http://www.securityfocus.com/bid/40973
http://www.opera.com/docs/changelogs/windows/1054/