Cyber Threat Intelligence (CTI) sharing has become a significant issue with the increasing number of cyberattacks. In CTI sharing, one entity (e.g., an organisation or a user) intends to share specific threat information to another entity that might otherwise be unavailable to another entity. However, this process needs to address many challenges, including privacy, trust, and accountability. In this paper, we propose a novel blockchain-based architecture that facilitates the secure dissemination of CTI data. The motivation for this study is to provide a solution that can efficiently address privacy, trust, and accountability when sharing CTI among organisations as well as maintaining an intelligence-based informed decisions. We discuss the current problems within the domain of CTI sharing using blockchain, and our proposal leverages the salient properties of the blockchain, e.g., decentralised, cryptographic keys, immutability, etc., to address those issues. We discuss the detailed design of the proposed architecture. We demonstrate that our approach offers a more effective and efficient way of CTI sharing that has the potential to overcome the trust barriers, data privacy, and accountability issues inherent in this domain.