Flight International (23.11-29.11 page 17)....the A350 has a two-part software architecture- the core domain for flight critical systems and the extension domain that includes the a380 inspired IFE system. Lange says the two domains could not be mixed for data security.
Access to the core from extension domain could allow passenger to spread viruses or hack hack flight systems. Boeing is using an avionics software "hardwall" to stop hacking on the 787.
Sounds to me that the designers treating this subject quite serious. Anything is possible.