Is CorVu 4.3 compatible with Oracle 12c?
I've checked various websites including the official one, but I didn't find anything related to Oracle for the version you have mentioned. The latest one is version 5.30 and doesn't specify either about oracle, but on a blog post on the official website, I've found that CorVu NG supports a wide number of databases including Oracle.
You can check the blog through the following link: http://forum.rocketsoftware.com/t/corvu-ng-overview/55/4
Additionally, get in touch with the official developers using http://www.rocketsoftware.com/contact?flag=contact&node=&product=&family=rocket&solution=&language=en&resourcetype=&resourceurl=&llactid=12112