Cloud computing is a rising technology that has gained significant attention over past decades. It offers various features such as-on-demand access, broad-network access, unlimited resource pool, etc. Despite so many merits, cloud computing has been full several challenges. Security indeed has remained one of the biggest challenges. Researchers, all over world, have been working on designing different types of security mechanism which can work on different levels on cloud environment. However, the literature on cloud security is quite wide and touches several issues pertaining to different stakeholders. The current study addresses the above issue by presenting a detailed review of challenges of security that are faced by different stake holders, such as cloud service provider (CSP), cloud user (CU), etc. This study will help the various researchers to find all security concerns at one place with critical reviews.