5G EC would play a key role on low latency services and traffic off-load services in 5G era. Several prominent factors would enlarge and complex the security risks to the network layer that supports 5G EC and even bring new security challenges to the network security operation. These factors would be the flexible network architectures of 5G, the variable deployment positions of EC, the various application scenarios, different types of users' private networks and access networks, etc. The boundaries among the telecommunication networks and the private networks would be more ambiguous, and the exposure surface would be expanded. Therefore, the security requirements and measures of the network layer including both of the telecommunication networks and the private networks would be recommended as telecommunication operators enjoying the benefit of EC.