Network Functions Virtualization (NFV) helps service providers become more agile and reduce their costs. However, NFV’s new architecture, operations, and openness create new security challenges. Those challenges must be overcome for service providers to scale NFV and earn its business benefits. This paper discusses a risk identification methodology, followed by a careful review of the top ve security risks when migrating services to NFV. The intent is to provide security practitioners with a basis for developing a documented risk dashboard in order to bring down the overall security risk to an acceptable level when migrating to NFV.