Opera does not require a fix for this issue. Opera always verifies that certificates are not revoked, and unlike other browsers Opera does not display sites as secure if access to revocation servers has been blocked by an attacker. Read more about this issue on the Security Group blog.
Opera will monitor the situation with DigiNotar according to Yngve Nysæter Pettersen (lead developer for security code)
The problem is currently handled by the standard revocation systems, OCSP and CRLs. We are continuing to evaluate the situation regarding DigiNotar, and may take steps regarding the trust settings for this Root.
I’m not quite sure which browsers he’s referring to in his comments, although I’d take a stab at IE. Chrome supports certificate pinning and HSTS preloading. Firefox supports OCSP as well as the older CRL methods, and HSTS.
Fundamentally, there are few differences between the browsers with regard to certificate verification, which is predominately locked into 1990’s technology and it’s really about time serious change occurred in the way things are done. Potentially, DNSSEC will help, but it’s by no means a panacea.
This is an enlightening read about the state of Certificate Revocation Lists and the Online Certificate Status Protocol. Both of which are seriously flawed technologies.