Security in Collaborative Driving: A Survey of Threats, Defenses, and Emerging Trends

Collaborative driving, in which autonomous vehicles cooperate with other vehicles and roadside infrastructure to improve safety, perception, and traffic efficiency, is emerging as a key paradigm for next-generation transportation systems. While such collaboration enhances situational awareness, it also introduces new security vulnerabilities across perception, communication, planning, decision-making, and control layers. In this survey, we present a unified taxonomy of security threats and defense mechanisms in collaborative driving systems, systematically organizing attacks and countermeasures across system layers. We further examine the integration of language models, including vision-based and multimodal reasoning models, into collaborative driving pipelines, highlighting the resulting security risks and design challenges. Finally, we identify key open research challenges, including cross-layer and end-to-end security, uncertainty-aware defenses, and real-world validation, outlining promising directions for future work toward secure and resilient collaborative autonomous mobility.