The Cascading Style Sheets (CSS) Extensions for XML implementation in Opera before 11.01 recognizes links to javascript: URLs in the -o-link property, which makes it easier for remote attackers to bypass CSS filtering via a crafted URL.
https://oval.cisecurity.org/repository/search/definition/oval%3Aorg.mitre.oval%3Adef%3A12045
http://www.vupen.com/english/advisories/2011/0231
http://www.securityfocus.com/bid/46036
http://www.opera.com/docs/changelogs/windows/1101/
http://www.opera.com/docs/changelogs/unix/1101/
http://www.opera.com/docs/changelogs/mac/1101/