With the continuous growth of the Internet of Things (IoT), LPWAN becomes more meaningful in order to have sustainable and extremely distributed connectivity while being energy efficient. In this review article, the security challenges that create serious risks in LPWAN deployments are examined, which are important in different IoT applications like urban infrastructure and industrial systems. By means of a critical summary of the recent research we disclose the multifaced security difficulties of such networks, including data integrity breaches, encryption weaknesses and unauthorized access. Review covers a lot, from the current security solutions and protocols to the weaknesses and hence the need for the innovative security frameworks that take into consideration the unique features of the LPWANs. We propose a novel security framework which inherently enhances the fault tolerance and accommodates the operational constraints that characterize the low-power networks. The paper outlines the current security issues while projecting possible future threats and provides a roadmap for the improvement of LPWAN protocols that will ensure the strength of the next generation IoT networks.