Fortunately I was home and heard the water shooting out of the pinhole leak and was quickly able to turn off the supply valve. Probably less than 5 gallons leaked so it was a relatively minor issue with no damage to my home or belongings. The fridge is about 15 years old and initially, I expected I'd be facing a more significant problem. Once I isolated the leak to the external supply line I went online and found the part number for the water filter housing and tube assembly. I ordered the part and it arrived within a week. It was an easy job to unscrew the fasteners holding the lines to the back of the fridge, remove the lower rear cover on the fridge to disconnect the line to the ice maker / water dispenser, unfasten the water filter housing from inside the fridge, and pull the tubes out through the inside of the fridge. I reversed everything, fishing the tubes from inside the fridge out the back, connected the tubes (using the brass connectors that came with the fridge), reattaching all the fasteners and turning the water back on. I saved a lot of money compared to hiring a repair company or buying a new fridge.