Peace,
If it intoxicates and clouds judgment then it falls under the core meaning of 'Khamr' which carries the meaning of concealment, to cover and something which clouds or obscures the intellect.
I have never taken Cannibis but from the little I do know, I do feel it clouds judgment and has the attributes of 'concealment' in the broadest sense. So therefore, I would be personally inclined to put it under that category.
Joseph.