An important consideration in software-defined networks (SDNs), is that one SDN application, through a bug or API misuse, can break an entire SDN. While previous works have tried to mitigate such concerns by implementing access control mechanisms (permission models) for an SDN controller, they commonly require serious manual efforts in creating a permission model. Moreover, they do not support flexible permission models, and they are often tightly coupled with a specific SDN controller. To address such limitations, we introduce an automated permission generation and verification system called VOGUE. A distinguishing aspect of VOGUE is that it automatically generates flexible permission models and yet is completely separated from the SDN controller implementation. To demonstrate the feasibility of our approach, we implement a prototype, evaluate its completeness and soundness, and examine its performance. In addition, to show the effectiveness of VOGUE, we demonstrate its use cases and security impact to SDN in the context of popular SDN controllers.