Opera before 10.00 trusts root X.509 certificates signed with the MD2 algorithm, which makes it easier for man-in-the-middle attackers to spoof arbitrary SSL servers via a crafted server certificate.
https://oval.cisecurity.org/repository/search/definition/oval%3Aorg.mitre.oval%3Adef%3A6442
http://www.opera.com/support/kb/view/933/
http://www.opera.com/docs/changelogs/windows/1000/
http://www.opera.com/docs/changelogs/solaris/1000/
http://www.opera.com/docs/changelogs/mac/1000/