WPA2 is the most robust security configuration available today for WiFi networks. It is widely used to secure enterprise WLANs. Interestingly, it is also being used to secure guest, municipal and public WiFi networks. In this paper, we present a new vulnerability found in WPA2 protocol which can be exploited by a malicious user to attack and compromise legitimate users. We also present a few attack mitigation techniques which can be used to protect genuine WiFi users.