What are Cerberus' powers and weaknesses?

Cerberus, as watchdog of Hades' kingdom, is allowed to eat any of the living trying to enter the Underworld and any of the dead trying to escape.

He has three heads.

However, that alone is not a power.

One recored power of Cerberus is that his saliva dripping on the ground when he barked at Heracules gave birth to a poisonous plant known as aconite (or wolfsbane).