The defrost drain in the freezer compartment is clogged. Normally the water would go down the drain into the drip pan at the bottom of the fridge but since it is blocked it is just spilling out into the fridge compartment. Remove the back panel in the freezer compartment to expose the drain and clean it out. You may have to manually defrost the freezer first. Try pouring some hot water down the drain and see if it comes out the bottom of the fridge where the drip pan is. If water is still pooling in the freezer compartment try inserting a rod of some sort into the drain or blowing the drain out using compressed air.

Good luck!