See

What kind of bugs are these Oracle bugs?

If there’s ways of breaking into the database, then fine, but first the attacker has to have broken into the systems and got behind the firewalls. I work for an Oracle shop and some of our customers got very excited about the security bugs.

What they had’t grasped was that in order to exploit them their entire infrastructure had to have been compromised as well. If people can break the Application Server and/or the Portal and get information they should’t then this is a serious issue, but vulnerabilities that involve messing with, say, SQL*Net, can only be exploited if everything else has been compromised first and an attacker can log into a machine or start looking at network packets. If this is the case, you really have more to worry about than you database.