Two main causes: clogged internal drain (defrost water can't reach drain pan) or worn door gasket. Both are easy technician fixes.
See if any of these signs match your device — each one increases the likelihood of this fault.
These are the causes we encounter while repairing Refrigerator leaking water — ranked from most to least common.
Internal drain clogged with food or ice
Drain pan full
Worn door gasket admitting warm air
Water inlet valve faulty (Ice Maker models)
Damaged water filter
Cracked Ice Maker water line
Any of the following = a danger signal — call now and don't try to fix it yourself.
On-site diagnosis, clear pricing before any work, and a documented 6-month warranty.