Symantec Java! JIT (Just-In-Time) Compiler for Netscape Communicator 4.0 through 4.8 allows remote attackers to execute arbitrary Java commands via an applet that uses a jump call, which is not correctly compiled by the JIT compiler.

The Sun Java Plugin capability in Java 2 Runtime Environment (JRE) 1.4.2_01, 1.4.2_04, and possibly earlier versions, does not properly restrict access between Javascript and Java applets during data transfer, which allows remote attackers to load unsafe classes and execute arbitrary code by using the reflection API to access private Java packages.