It is understood the attack on Huntley happened in a prison workshop just before 09:30 GMT.
An air ambulance was dispatched to HMP Frankland, but the North East Ambulance Service spokesperson said the injured inmate was taken to hospital by road.
Durham Constabulary confirmed a police investigation is under way and that detectives are liaising with staff at the prison.
“Police were alerted to an assault which had taken place within HMP Frankland in Durham this morning,” a Durham police spokesman said.
“A male prisoner suffered serious injuries during the incident and was transported to hospital.”
The deaths of 10-year-olds Jessica and Holly in the quiet Cambridgeshire village of Soham on 4 August 2002 shocked the country.
