Implementing Zero Trust Security in Multi-Cloud Microservices Platforms: A Review and Architectural Framework

The widespread adoption of multi-cloud infrastructures and microservices architectures has redefined enterprise computing by enhancing scalability, modularity, and service delivery. However, this decentralization has also introduced expanded threat surfaces and complex security challenges that traditional perimeter-based models can no longer address effectively. This paper presents a comprehensive review and a proposed architectural framework for implementing Zero Trust Security (ZTS) in multi-cloud microservices environments. Beginning with a synthesis of existing literature and industry best practices, the study identifies critical vulnerabilities and limitations in current security approaches. It then explores the foundational principles of Zero Trust—including least privilege, continuous verification, and identity-centric access control—and how they apply within distributed cloud-native systems. The proposed framework incorporates core security components such as identity and access management, centralized policy engines, micro-segmentation, and service mesh integration to enable fine-grained, context-aware access enforcement. Designed for cloud-agnostic compatibility, the architecture facilitates secure workload mobility and dynamic service discovery across heterogeneous environments. Practical considerations, including performance impact, interoperability challenges, and governance implications, are also discussed. Although the framework offers a strategic path toward resilient multi-cloud security, it acknowledges limitations in empirical validation and implementation variability. The paper concludes by recommending future research directions in adaptive trust scoring, AI-driven policy enforcement, and Zero Trust extensions to edge-cloud systems, thus contributing to the ongoing evolution of secure cloud-native computing.