The man who raped and murdered Irish woman Jill Meagher in September 2012 was stabbed during an altercation on Thursday evening, according to reports.
Bayley is serving at least 40 years in prison for the rape and murder of Meagher.
Corrections Victoria confirmed to The Irish Times that a prisoner had received "minor injuries" following an incident and was treated at the scene on Thursday.
A number of Australian media outlets are reporting that a fork was used to stab Bayley at Barwon Prison in West Melbourne.
The Herald Sun in Austrailia reported that Bayley was attacked inside Barwon Prison, west of Melbourne, on Thursday and suffered minor injuries.
The 46-year-old has spent much of the past five years in protective custody because of concerns he would be targeted by other inmates, according to the newspaper.
He is believed to have been in a protection unit - the Hoya unit - for prisoners at high risk of being attacked, when he was targeted.
According to The Herald Sun, Bayley is particularly “loathed” by his fellowinmates because his crimes sparked a toughening of the parole regime.
Ms Meagher who was originally from Co Louth, was murdered and raped while walking home from a pub in Brunswick, a suburb of Melbourne, in September 2012.
Bayley received a life sentence for the 2012 rape and murder of Meagher and was jailed for at least 35 years for the attack.
He was found guilty in May 2015 of three more violent rapes and was sentenced to 18 years in jail for those crimes.