In this work, we examine the interference alignment performance of a multi-input multi-output (MIMO) cognitive radio (CR) network in the presence of multiple secondary users. In the proposed architecture, it is assumed that linear interference alignment (IA) is used at the primary system to alleviate the interference between primary and secondary networks. Although, linear IA can surpass the interference in CR considerably, interference leakages may occur due to fast fading channel. Herein, we derive the closed form outage probability expression considering the interference leakage occurred in the primary system. The results which are validated with Monte-Carlo simulations show that interference leakages can deteriorate both system performance and diversity gains considerably.