In Eclipse OpenJ9 up to and including version 0.23, there is potential for a stack-based buffer overflow when the virtual machine or JNI natives are converting from UTF-8 characters to platform encoding.
In Eclipse OpenJ9 prior to version 0.21 on Power platforms, calling the System.arraycopy method with a length longer than the length of the source or destination array can, in certain specially crafted code patterns, cause the current method to return prematurely with an undefined return value. This allows whatever value happens to be in the return register at that time to be used as if it matches the method's declared return type.