Abstract Despite the fact that VANET brings huge benefits they present many challenges in terms of communication security. Traffic safety and management require real-time information and can influence life or death decisions. Without security, the system is wide open to a number of attacks, the spread of false warnings but also the suppression of real warnings leading to traffic accidents. The article presents the classification of different types of attacks in VANET. In addition, there are different types of adversaries and attackers. We focus on demonstrating network attacks in order to assess their impact on parameters affecting the quality and availability of services such as delay, throughput and data loss. Thanks to the implementation of the transport protocols UDP, TCP and the ICMP service protocol, we were able to monitor the impact of attacks on individual data transmissions depending on the growing probability of packet infiltration. The increasing probability of infiltration leads to a complete degradation of the quality and availability of services, which also reduces the reliability of the network. In general, the purpose of this article is to provide information about security and privacy in VANET and to point out to security risks that may lead to suppression of the availability of services and increase the complexity of the network.