The schoolgirl's murderer Sarah Payne was assaulted in her cell in a high-security prison.
Eighty-year-old Sarah Payne was kidnapped and murdered by the condemned pedophile Roy Whiting in West Sussex in 2000.
Whiting, now 59, was convicted in 2001 of his abduction and murder and will serve for a minimum of 40 years.
The Sun newspaper reported being hospitalized after being "stabbed by two convicted murderers with improvised blades" at HMP Wakefield.
A spokesperson for the Prison Service said: "An inmate of HMP Wakefield was attacked on Thursday evening and received hospital treatment.
"The prisoner is again in prison under stable conditions and the incident is investigated by the police".
In a statement, West Yorkshire police said she was called to prison at 7:15 pm GMT on Thursday to report that a prisoner had been assaulted.
He said the wounds "were not life threatening" and an investigation was taking place.
Sarah, who lived in Hersham, Surrey, disappeared from a cornfield near her grandparents' home in Kingston Gorse, West Sussex, in July 2000.
He had played with his brothers and sisters before slipping through a hedge in a country lane and disappeared.
His body was found 17 days later in a field about 15 miles away near Pulborough.
After being convicted in 2001, the trial judge, Judge Richard Curtis, said he believed Whiting was "an evil man" and "a cunning and cunning liar".
In July 2011, Whiting was stabbed in the eyes of Wakefield Prison by another inmate, sentenced by the assassin Gary Vinter.
Vinter admitted the attack.
In 2002, Whiting was attacked with a razor blade by roommate Wakefield Rickie Tregaskis.