Security and Privacy Challenges in Multi -Cloud Environments : A Comprehensive

Abstract

The rapid adoption of multi -cloud computing in which organizations distribute workloads and data across two or more cloud service providers (CSPs) has introduced a distinct and rapidly evolving class of security and privacy problems that differ materially from those of single - provider or simple hybrid -cloud deployments. This paper presents a review of the security and privacy challenges that arise in multi -cloud environments synthesizing recent academic literature and industry research published primarily between 2018 and 2026. The review is organized around six pillars: data security and confidentiality, identity and access management (IAM) network security and attack -surface expansion, privacy -preserving computation, regulatory compliance and data sovereignty and the emerging role of Zero Trust Architecture (ZTA) as a unifying defense paradigm. For each pillar representative studies are summarized, compared and critically discussed, culminating in a analysis table that maps challenges to proposed solutions and their limitations. The review concludes by identifying research gaps, including the lack of standardized cross -CSP security interfaces the shortage of empirically validated Zero Trust deployments in production multi -cloud settings and the unresolved tension between regulatory data - sovereignty requirements and the operational flexibility that motivates multi -cloud adoption in the first place. This review is intended as a foundation for researchers and practitioners seeking to design resilient privacy -preserving and regulation - compliant multi -cloud architectures.