A manet can be described as a group of random wireless nodes connected to each other forming a network with unrestricted mobility and no infrastructure. Mobile ad hoc networks (manet) are self configuring, wireless, dynamic and have no central administration. At a point where all these features make manet an awesome concept, they also create some loopholes in the security management of these ad hoc networks. This paper will primarily focus upon the security issues of the manet and their feasible solutions. The results enable us in risk minimization. Keywords: Manet, attacks, dos, black hole, wormhole, byzantine, rushing, sinkhole, solutionsINTRODUCTION As the advancements of the performance in wireless computer technology, MANETs have evolved as an advanced mobile wireless computing solution. A MANET is an infrastructure less, not centrally administered, self-organizing system of mobile nodes connected without wires. The key idea behind the development of the mobile ad-hoc networks is to provide a robust and efficient operation in a mobile wireless network. The devices of the MANET are free to move, enter and leave the network anytime which lets the MANET to have a dynamic topology, and hence the network becomes decentralized.The communication in MANET takes place by using multi-hops path i.e. the nodes that are in range of radio frequency of each other communicates directly and for communication with other nodes those are not in the range of radio frequency, intermediate nodes are being used. So to communicate with each other the nodes dynamically establishes a path from source to destination. Due to this feature of MANET and open communication medium makes them highly vulnerable. The main objective of this paper is to study the security attacks and vulnerabilities of the MANETs on different layers of protocol stack.