The industry trend towards open, disaggregated systems, as embodied in the work in O-RAN ALLIANCE, is to gain significant advantages over traditional mobile infrastructure, such as flexibility to create highly customized solutions with best-of-breed components; efficiencies driven by the economies of scales; increased competition; – and innovation driven by lower barriers to entry. As mobile networks and mobile cloud systems become ever more open and disaggregated and are sourced from an increasingly larger set of suppliers, security vulnerabilities associated with other similar systems – notably modern IT infrastructure – are likely to become an increasingly significant threat. Considering the expected pervasive reliance on open, disaggregated systems in 6G networks, the importance of security is significant and therefore warrants a focused discussion. This report examines threats to 6G networks and recommends controls and mitigations to make 6G networks secure from existing and emerging threats.