The most common site of leak in CSF rhinorrhoea is -
Leakage of CSF is most commonly seen in the anterior cranial fossa at the level of the cribriform plate as it is extremely thin. (Ref: Diseases of nose ear and throat; Logan Turner; pg 28)
Sphenoid sinus
Frontal sinus
Cribriform plate
Tegmen typmani
Nose and paranasal sinuses