Widespread communication between vehicles and the outside world and the trend in smart vehicle technologies accelerated research in the field of vehicular ad hoc network. Along with what the system can do, resolutions are also presented for the security vulnerabilities of the system. These involve the detection of malicious vehicles that can harm the system with false information or the prevention of their possible damage. Trust- and recommendation-based models are one of the main approaches. It is known that these proposed models have been tested against attacks such as on/off, bad-mouthing, and correspondingly single or collaborated attacks in general trust systems. In trust-based models, certain methods are used to prevent false information for the stability of the system and to limit devices that spread the forgery. In this study, for the first time, we adapted the reputation trap (RepTrap) attack that was proposed for recommendation systems in social networks to VANET systems those use reputation/trustworthiness for their trust models. Thus, we have presented a vulnerability that reduces the reputation of benign devices as they are considered as malicious due to the taken security measures. The effectiveness of the attack was demonstrated on three recent studies, and its feasibility was verified on simulation. Some preliminary prevention mechanisms are also proposed.