Officially, there is no new Android version available (because HTC sucks at updating their phones).
Unofficially, there are new versions based on Android 4.1 or even 4.2 if you're rooted. If you're not rooted, then ignore the second solution. If you are rooted (which I doubt you are since you're asking this question), then just look for the respectful ROM that's based on whatever Android version you want. Hope this helped.