Why do asynchronous EJB3 calls periodically lose their security context on JBoss EAP 6?

Issue

Why do asynchronous EJB3 calls periodically lose their security context on JBoss EAP 6?

We have a stateless bean that calls an @Asynchronous method in another stateless bean multiple times in order to get better performance. Sometimes it works, but sometimes we get the following exception:

javax.ejb.EJBAccessException: JBAS013323: Invalid User: java.util.concurrent.ExecutionException: javax.ejb.EJBAccessException

It seems as if the asynchronous threads are reused and that the security context is lost somehow.

Our environment looks like the following:

client --> nodeX --- (remoting) --> nodeY (Asyc Method)

Currently we are using JBoss EAP 6.3.3 GA but we also experienced the same behavior in JBoss EAP 6.1.0.GA.