DIAGNOSIS The internal drain tube has come loose or the drain pump housing is cracked. This is not a leak from the water reservoir.
FIX Unplug and empty the machine. Tip it back to examine the base. You'll see a small white drain pump with two silicone tubes attached: one from the ice chamber, one leading out the back. Check where these tubes connect to the pump. Push them on firmly. If the connections are tight, the pump housing itself may have a hairline crack from freezing.
IF THAT DIDN'T WORK The leak could be from the water reservoir seal. Remove the reservoir. Inspect the orange silicone gasket where it seats into the machine. Ensure it's not twisted or torn. A missing or damaged gasket causes water to bypass the reservoir and drip inside the cabinet.
HEADS UP Leaks cause electrical shorts. Do not operate the machine until the leak is found and fixed. Dry the interior completely with a fan before plugging it back in.