Recent research in security issues and defense mechanisms for Vehicular Ad Hoc Networks (VANETs) focuses on addressing vulnerabilities that arise from high mobility, dynamic topology, and the open wireless environment of vehicular communication systems. Key studies explore mitigation techniques for attacks such as Sybil, blackhole, wormhole, denial-of-service, and eavesdropping through lightweight authentication, blockchain-based trust management, and AI-driven intrusion detection frameworks. Researchers are also developing privacy-preserving models that leverage federated learning and fog computing to detect anomalies in real time while maintaining low latency. Hybrid cryptographic protocols and distributed trust systems are being implemented to enhance data integrity, confidentiality, and availability in cooperative communication. These advancements collectively aim to build resilient, adaptive, and intelligent defense architectures that ensure secure data exchange and reliable connectivity in next-generation vehicular networks.