Wireless Mesh Networks (WMNs) have been extensively studied by researchers for the last few years because of their engrossing characteristics of being self-healing, selforganizing and providing continuous connectivity. While many security issues present in these networks have already been discussed, one major problem that still lacks sufficient investigation is securing the channel assignment (CA). While the quondam CA schemes have mostly used dynamic CA (DCA) methods, these schemes do not consider the security threats that exist while assigning these channels to the available wireless links. In this paper, we introduce an efficient and lightweight framework called PiCAT for securing DCA in multi-radio and multi-channel WMNs.