I used to have cats that could open doors. They would stand as so and then jump up and grab the doorknob with there front paws and swing on it till the door came open.
@kooroe Spock now has this thing after we stayed in the RV waiting for the house to finally close and he opened a vent door under the bed, where he opens all cabinet doors in the house. I've had to put 10lb velcro on every door. It worked, but the little brat still tries.