Opera before 10.00 on Linux, Solaris, and FreeBSD does not properly implement the "INPUT TYPE=file" functionality, which allows remote attackers to trick a user into uploading an unintended file via vectors involving a "dropped file."
https://oval.cisecurity.org/repository/search/definition/oval%3Aorg.mitre.oval%3Adef%3A5679
http://www.opera.com/support/kb/view/931/
http://www.opera.com/docs/changelogs/solaris/1000/