My FIRST guess would B a Leak-If it's just water, U could have a roof leak or a broken windshield - IF IT'S ANTIFREEZE u HAVE A bad HEATER CORE..or YOUR ac drain COULD B CLOGGED.
If it's the front passenger side ,I would say your heater core is leaking .
Windshield seal? Lower door seal? Hole in floor ?
The 2010 Nissan Pathfinder has .
It could be the heater core leaking.
Heater core has failed.
clogged or damaged catalytic converter
Heater core
most likely cause is your heater core leaking
Leak in heater core
The ac drain is plugged. The drain hose is on the firewall on the lower passenger side. ...that, or your heater core is leaking.
It fastens to a pass through stud at the passenger floor.
maybe the exhaust pipe under it is heating up and the floor is very thin