The component JNDI environment for a Stateless session bean does not appear to be read-only.

I have a SLSB running in 3.2.6.

It attempts to modify it's ENC (java:comp/env environment) and succeeds. I.e. the following succeeds:

InitialContext ic = new InitialContext();
Context envCtx = (Context)new InitialContext().lookup("java:comp/env");
envCtx.bind("foo", "bar");
log.debug("Worked!!");

Also bind stuff into the context works.

I haven't tried with other types of EJB.

According to the EJB 2.0 spec (Sec. 20.2.4) an enterprise beans's environment should be read-only.