In this work we study the need of template protection to provide security and privacy in text-dependent pass-phrase voice authentication systems. For this purpose, we analyze the robustness of two state-of-the-art speaker verification systems against attacks performed using input data generated from a compromised voice template. This analysis shows that compromised templates can be used to gain unauthorized access to authentication systems, when these systems use the same speaker verification technology, background models and pass-phrase as the one from which the compromised template was stolen. However we also show that the compromised template may not be helpful to attack an authentication system which uses a speaker verification technology or pass-phrase different from those considered in the system the template was obtained from. This fact facilitates the fulfillment of the main requirements that a protected template should meet to guarantee user privacy: irreversibility and unlinkability. Finally we propose a set of guidelines for the design of voice authentication systems that enable the preservation of user privacy and provide revocability measures in case a template is compromised.