It happened around 3 p.m. Monday, Dec. 25 in Litchfield County on Route 44 (Canaan Road) in the town of Salisbury.
The vehicle was traveling eastbound in the area of Twin Lakes Road when the driver lost control and traveled across the westbound lane and shoulder, subsequently exiting the roadway, where it collided with a tree, Connecticut State Police said.
The passenger in the vehicle was pronounced dead at the scene. He's been identified as Litchfield County man Avery Nelson, age 23, of Norfolk.
The driver, a 20-year-old town of Canaan man, suffered serious injuries, police said.
Any witness to the crash is asked to call state police Troop B at 860-626-1820.
Click here to follow Daily Voice Stratford and receive free news updates.