My dishwasher attaches to the cabinets on the side via a screw. This hole has become a little stripped, is there a way to fill it in and then screw in to it again? I can't change the location of where the dishwasher attaches.
Clean out the hole of debris and then carve a tapered peg from another piece of wood that will start into the hole. Fill the hole with wood glue and then pound in your peg. Let it dry overnight and then cut off the remainder of the peg flush with the surface. At this point you can drill a new pilot hole for your screws.
If you are lacking a wooden peg or the skills to make one use round wooden toothpicks. Coat the toothpicks with woodglue. Place as many toothpicks in the hole as will fit. Gently tap in one more with a hammer. Break off any bits of toothpick that protrude from the hole. After the glue has dried, reinstall the screw.
If you have access to the inside of the cabinet you could replace the wood screw with T-nut and a machine screw.
You would need to drill the hole to fit the T-nut and place the T-nut on the inside of the cabinet.
Again, this only works if you have access to both sides of the cabinet wall.
I agree with using wooden pegs, matchsticks, or toothpicks to fill the holes, but rather than wood glue I recommend epoxy because it's better at filling spaces, and doesn't need clamping to form a strong bond. I'd use something like a small screwdriver to fill each hole with epoxy, liberally coat the peg/matchstick/toothpicks with more epoxy and pound them in, cut them off flush, then stick a piece of tape over the hole to keep the epoxy in place until it hardens. (Clean up the mixing surface and tools with alcohol.)
The quickest and easiest solution:
Use a bigger screw.
A larger diameter screw of the same length will fill the hole.
I have done this to hold my own dishwasher in, and in numerous other scenarios. I know a lot of cabinet material is crappy particle board which is not very durable.
Also, in cases where you are not worried about the screw coming out the other side (door hinges for example), a longer screw will work as well (and better).
Tap a plastic wall plug into the hole, the sort you'd normally use in brick or concrete walls, or a screw in wall plug if it's a cavity wall.