Opera before 10.60 does not properly restrict certain interaction between plug-ins, file inputs, and the clipboard, which allows user-assisted remote attackers to trigger the uploading of arbitrary files via a crafted web site.
https://oval.cisecurity.org/repository/search/definition/oval%3Aorg.mitre.oval%3Adef%3A11862
http://www.vupen.com/english/advisories/2010/1673
http://www.vupen.com/english/advisories/2010/1664
http://www.opera.com/support/search/view/958/
http://www.opera.com/docs/changelogs/windows/1060/
http://www.opera.com/docs/changelogs/unix/1060/