Mobile ad hoc networks (MANETs) are collections of wireless mobile devices with restricted broadcast range and resources, and no fixed infrastructure. Communication is achieved by relaying data along appropriate routes that are dynamically discovered and maintained through collaboration between the nodes. Discovery of such routes is a major task, both from efficiency and security points of view. Recently, a security model tailored to the specific requirements of MANETs was introduced by Acs, Buttyan, and Vajda. Among the novel characteristics of this security model is that it promises security guarantee under concurrent executions, a feature of crucial practical implication for this type of distributed computation. A novel route discovery algorithm called endairA was also proposed, together with a claimed security proof within the same model. In this paper, we show that the security proof for the route discovery algorithm endairA is flawed, and moreover, this algorithm is vulnerable to a hidden channel attack. We also analyze the security framework that was used for route discovery and argue that composability is an essential feature for ubiquitous applications. We conclude by discussing some of the major security challenges for route discovery in MANETs.