The water created by the defrost cycle of the refrigerator goes down a tube and is directed into a collection tray at the bottom of the refrigerator. By design, this water is evaporated off by the warm air circulated across it as the condenser fan runs. Normally, the condensate water created from the defrost cycle is not enough to overflow this tray. If the tube that carries the water to the bottom tray is leaking or loose, it may cause this problem. The tray that collects the water is heavy duty. It is unlikely that it is cracked and leaking.
Other sources of leaking could be from your ice maker. The water supply tubing in this system could be leaking. If you shut off the water supply to the refrigerator and the leak stops, it would indicate that the leak is coming from your ice maker water supply system.
I recommend that you pull the refrigerator forward and check the ice maker water supply tubing. Also check the drain tube and collection tray. You may find the source of your water leak in one of these areas. If not, you may need a service technician to diagnose and repair your refrigerator.