Significant advancements in Cooperative and Autonomous Driving via Vehicle-to-everything (V2X) communications owe much to the rapid expansion and technological progress in vehicular communications, promising benefits like enhanced traffic flow and reduced energy consumption. However, this reliance on connected vehicles opens new security vulnerabilities. This study provides a comprehensive overview of challenges in existing vehicular communications, with a specific focus on security attacks categorised by their impact on MAC, routing, and cross-layer levels. To ensure secure vehicular communication, we analyse existing solutions for both single and cross-layer attacks, evaluating their strengths and limitations from a security standpoint. Additionally, we innovate by addressing vulnerabilities across MAC, routing, and cross-layer interactions, offering practical insights and a unique approach to mitigating their combined impact. Our findings suggest that enhancements are needed for MAC layer security in TDMA protocols, and that routing protocols must be designed with better security features to manage high overheads and real-time requirements.