Gowdiak has not released the details of the vulnerability, but did state that it is related to the new Reflection API that was introduced into Java SE 7, and that successful exploitation allows an attacker to reliably bypass Java's security sandbox. But what is weird is that the attack has been in the public knowledge for at least 10+ years.
“It's one of those risks one should protect against in the first place, when new features are added to Java at the core VM level," Gowdiak wrote on Bugtraq.
Gowdiak claims that his company's proof-of-concept code works on the most recent version of Java SE 7, Update 25 and earlier. Gowdiak questioned how seriously Oracle is taking security, given he believed that the flaw should have been picked up rather easily.
He argued that its security assurance procedures, if they existed, should have quickly identified the issue and eliminated it before Java SE 7 was released.