From the abstract, 
   This document defines an information model and a YANG data model for
   Registration Interface between Security Controller and Developer's
   Management System (DMS) in the Interface to Network Security
   Functions (I2NSF) framework to register Network Security Functions
   (NSF) of the DMS with the Security Controller.

The document contains a well-written security considerations section that describes potential threats and mitigations. I have no experience with YANG, but from a security point of view, I see no issues with this document.