The most common site for CSF rhinorrhoea is -
Ethmoidal sinuses
Maxillary sinuses
Frontal sinus
Tegmen tympani
The most common site of traumatic CSF rhinorrhoea is the fracture of that pa of the cribriform plate which forms the roof of the ethmoid sinus. (Ref: Cummings, 6th edition, pg no. 804)
Nose and paranasal sinuses