Yes, it would be a challenge for a kitten, would need a lower sided box until the kitten grows bigger.

I chose the higher sides (18 inch sides) because I have one naughty girl who likes to stand up and pee all over the wall and floor.

She doesn't do it all the time. When she does, she starts in a normal squat, but as she pees she allows her bottom to gradually rise up until she is standing and the pee is shooting all over the place.

I now have normal littler boxes and the big tote ones. She only does her naughty standing pees in the tote ones now. If she uses a regular box she stays squatted like a nice modest girl.