Recently, security and privacy issues have become barriers to the adoption of cloud computing. The main risks associated with cloud environments are the loss of control, lack of trust, and multi-tenancy. They raise serious concerns over privacy and security because the data and resources are located out of the users' boundary; the access control policies are enforced by a semi-trusted cloud; and the resources are shared between tenants. Because of the present issues of privacy and security, many studies have introduced solutions to protect the data stored in a cloud and prevent privacy violations. In this paper, we analyze the recent work on security and privacy in a cloud environment based on the related outlines provided by the Cloud Security Alliance (CSA); and provide an overview of the main mechanisms that have been used. This overview shows the existing research trends and presents open issues that offer a foundation for additional research in the cloud field.