The latest edition of 2600 magazine is running a item could “A Back Door to Your Oracle Database”. I have not received my copy of the magazine but I am sure I will be reading it.
It is however not a big surprise to me that there are bugs on the security of oracle. Even do it is clamed to be “run by the top 10 of the top 10 world banks” and unbreakable and stuff. At least if you are buying their advertisement, the security has some leaks. Not in the database alone but also in other products. I have put up an article on a security bug I discovered and placed this on my website.
You can have a good read on Oracle Istore security on my personal website.