Opera before 11.01 does not properly handle redirections and unspecified other HTTP responses, which allows remote web servers to obtain sufficient access to local files to use these files as page resources, and consequently obtain potentially sensitive information from the contents of the files, via an unknown response manipulation.
https://oval.cisecurity.org/repository/search/definition/oval%3Aorg.mitre.oval%3Adef%3A12296
http://www.vupen.com/english/advisories/2011/0231
http://www.securityfocus.com/bid/46036
http://www.opera.com/support/kb/view/984/
http://www.opera.com/docs/changelogs/windows/1101/
http://www.opera.com/docs/changelogs/unix/1101/
http://www.opera.com/docs/changelogs/mac/1101/