On April 15, 2014 Oracle has released Java 7 Update 55, with this update the security baseline was moved to Java 7 Update 55. For Sametime users this means when they download a Java applet they will be prompted with a security dialog. To resolve this issue Sametime users will need to upgrade to Java 7 Update 55, and Sametime Admins will need to verify that the following technote has been followed: http://www-01.ibm.com/support/docview.wss?uid=swg21654503
Since Java 7 Update 10, there have been hardcoded expiration dates set in the JRE. These force the system to display the security dialogs when a JRE expires. Unfortunately each new release means having to deal with this issue all over again. Currently no known methods exist to bypass this issue with new releases of Java. Admins can plan for this issue to reoccur on July 15, 2014 when the next expiration date is set.
With Java 7 update 45, the addition of the "Caller-Allowable-Codebase" attribute was added to the manifest.
Additional Information on this issue:
Updated Security Baseline (7u45) impacts Java 7u40 and before with High Security settings
Understanding the new security in Java 7 Update 11
Java 7 Update 45 Release Notes
JAR File Manifest Attributes for Security