Cloud computing is a distributed computing paradigm capable of providing agile IT services to individual users and organizations. Cloud computing is a technology which will facilitate companies or organizations to host their services without worrying about IT infrastructure and other supporting services. Cloud computing providers can build large data centers at low cost due to their expertise in organizing and provisioning computational resources. Cloud security has emerged as arguably the most significant barrier to faster and more widespread adoption of cloud computing. Indeed, cloud computing suffers from threats and vulnerabilities which hinders the users from trusting it. In this paper, the authors explore the vulnerabilities and threats of cloud storage one of the domains of cloud computing that affects the different cloud service model.