Those concerned about security of Java PaaS (Platform as a Service) or cloud services in general might find the following information interesting.
Security Explorations discovered multiple security vulnerabilities in the environment of Oracle  Java Cloud Service .
Among a total of 28 issues found, there are 16 weaknesses that make it possible to completely break Java security sandbox of a target WebLogic server environment. An attacker can further leverage this to gain access to application deployments of other users of Oracle Java Cloud service in the same regional data center.
The nature of the weaknesses identified in Oracle's service indicates that it was not a subject of a thorough security review and penetration testing prior to the public offering. They illustrate known and widely discussed security risks related to Java . They also expose weak understanding of Java security model and attack techniques by Oracle engineers.
More information regarding our research can be found at the official pages of SE-2013-01 project:
We hope the next time Larry Ellison is about to choose between boats and work , work is gonna win as obviously certain areas at Oracle need actual work, not the improvisation.
Best Regards, Adam Gowdiak
Security Explorations http://www.security-explorations.com "We bring security research to the new level"
References:  Oracle Corporation http://www.oracle.com  Oracle Java Cloud Service https://cloud.oracle.com/mycloud/f?p=service:java:0  SE-2012-01 Project, Security Vulnerabilities in Java SE http://www.security-explorations.com/en/SE-2012-01.html  Ellison ditches own cloud keynote for billionaires' America's Cup boat race http://www.theregister.co.uk/2013/09/24/oracle_openworld_walkout/