The Java Plug-in in Java SE Development Kit (JDK) and Java Runtime Environment (JRE) 5.0 Update 17 and earlier; 6 Update 12 and earlier; and 1.4.2_19 and earlier does not prevent Javascript that is loaded from the localhost from connecting to other ports on the system, which allows user-assisted attackers to bypass intended access restrictions via LiveConnect, aka CR 6724331.  NOTE: this vulnerability can be leveraged with separate cross-site scripting (XSS) vulnerabilities for remote attack vectors.