Because of the development of numerous security-sensitive applications in many areas using WSNs, wireless sensor networks (WSNs) security is a subject of significant significance. Compared to traditional wireless and wired networks, WSNs have a variety of additional vulnerabilities, such as a dynamic network topology, the broadcast nature of the medium, resource-constrained nodes, a significant network size, and a lack of physical infrastructure. WSNs are more vulnerable to various attacks than wired communications because of the open communication environment, including passive eavesdropping operations that lead to intercepted transmissions and active jamming attacks that lead to transmission interruption. These new flaws allow the opponent to carry out more severe and complex assaults. As a result, a comprehensive examination of possible attacks against WSNs is needed. As a result, the purpose of this article is to examine wireless security weaknesses and threats in order to develop a reliable and efficient defense method for improving WSN security. First, we will go through the security problems and needs of wireless networks. The next section of the paper examines security flaws in wireless networks and groups probable WSN attacks into OSI protocol levels. Finally, a number of unsolved technical issues are mentioned, along with future work in WSN security.