Opera before 11.00, when Opera Turbo is enabled, does not display a page's security indication, which makes it easier for remote attackers to spoof trusted content via a crafted web site.
http://www.opera.com/docs/changelogs/windows/1100/
http://www.opera.com/docs/changelogs/unix/1100/
http://www.opera.com/docs/changelogs/mac/1100/
http://secunia.com/advisories/42653
http://lists.opensuse.org/opensuse-security-announce/2010-12/msg00006.html