Arsonists set fire to a van as it was parked on the driveway of a man's home, but the flames spread to his house, endangering his family inside.
The van was parked outside the house in Stewards Avenue, Widnes, when the fire was started deliberately at about 0400 BST on Sunday.
A 25-year-old man was inside the house with his wife and three young children at the time.
Cheshire Police said the fire had been extinguished and no-one had been hurt.
The potential for serious injury was "very real", the force said.
Police are appealing for witnesses to the attack to contact them.