We support STIX 1.x and TAXII 1.1

We're targeting to release this in Jul-Aug 2017

STIX / TAXII support on FMC will be part of the next release. It's currently in final testing and targeted for CY H1 2017.

We're working on a STIX/TAXII connector for Firepower Management Center and are currently planning to release it in CY Q1 2017.