The source told CNN that Koureiris, who was arrested by Saudi authorities at age 13, could be released by 2022.
Kouriri's punishment includes the time spent in his arrest in 2014, with the last four years of probation, leaving him three years in prison.
CNN reached the Saudi government for comment.
He is charged , to accompany his brother, activist Ali Kouriris, to a motorcycle to a police station in the eastern part of Saudi Arabia, where Ali claims to have threw Molotov cocktails in the facility, and his other alleged crimes include visiting at his brother's funeral, which later became a rally.
Koureiris denied the allegations and stated that the confessions that the Prosecutor's Office had largely invoked had been compulsorily received
At the time of the arrest, the attorneys and activists believe Curirius is the youngest known political prisoner in Saudi Arabia
Murtaja Qureiris is a Shiite family in the eastern province of the majority of Sunni Saudi Arabia. the Shiite minority of the kingdom.