IoT devices often operate unsupervised in ever-changing environments for several years. Therefore, they need to be updated on a regular basis. Current approaches for software updates on IoT, like the recent SUIT proposal, focus on granting integrity and confidentiality but do not analyze the content of the software update, especially the IoT application which is deployed to IoT devices. To this aim, in this paper, we present IoTAV, an automated software analysis framework for systematically verifying the security of the applications contained in software updates w.r.t. a given security policy. Our proposal can be adopted transparently by current IoT software updates workflows. We prove the viability of IoTAV by testing our methodology on a set of actual RIOT applications. Experimental results indicate that the approach is viable in terms of both reliability and performance, leading to the identification of 26 security policy violations in 31 real-world RIOT applications.