Due to their diverse applications, including safety, welfare, and improving traffic efficiency, intervehicle ad-hoc networks have been extensively studied. Globally, road congestion, accidents, fuel consumption, and environmental pollution caused by the large number of vehicles have become serious problems that have caused a lot of human and financial losses. Intelligent Transportation Systems (ITS) have introduced VANETs in order to overcome these problems. In vehicular ad hoc networks (VANETs), vehicles equipped with wireless interfaces can communicate with other vehicles and with fixed roadside equipment via mobile ad hoc networks (MANETs). Messages are transmitted over open wireless channels in VANETs. Malicious nodes target these networks to protect them from various attacks, such as interference, eavesdropping, spoofing, denial of service, sybil, black holes, worm holes, gray holes, etc. Security of VANETs is therefore one of the most significant issues. Security issues, attacks, attackers, and secure routing protocols in VANETs are discussed in this article, as well as available solutions to solve security issues.