The top on the list of the database vulnerabilities are deployment failures, when company are usually testing a software, they usually test to see if it is doing everything that it was designed to do, they never check to see if it is doing something that it was designed to do. Then there are the broken databases where most business don't keep their systems regularly patch leaving the database vulnerable.
There are a lot more of theses vulnerability that administrators need to keep in mind and look to best practices to make sure they are up to date some more of these vulnerabilities include data leaks when data is not encrypted with SSL or TLS, SQL Injections and Database inconsistencies.
http://www.zdnet.com/the-top-ten-most-common-database-security-vulnerabilities-7000017320/