Device-to-device (D2D) communication that allows direct communication between nearby mobile devices without traversing through the base station is a potential solution to solve the problem of safer and faster data rate communication. This review paper comprehensively explores the security aspects of D2D communication, focusing on the vulnerabilities, threats, and existing security mechanisms. In addition, it provides an in-depth analysis of the security challenges in D2D communication, including eavesdropping, data integrity, authentication, and privacy concerns. Furthermore, it also delves into the potential security risks associated with different D2D communication scenarios, such as public safety, proximity-based services, and ad-hoc networking. Toward the end, this survey discusses the open research challenges and future directions in securing D2D communication, highlighting the need for robust security protocols to mitigate the evolving threats in this dynamic communication paradigm. The findings presented in this survey aim to provide researchers, practitioners, and policymakers with a comprehensive understanding of the security landscape in D2D communication, thereby contributing to the successful deployment of secure and reliable D2D communication systems.