The 45-year-old walked free from court, after a judge backdated the sentence on his latest conviction -- for assaulting a young woman.
From Mountjoy Square in the north inner city, Moore has served lengthy time for a number of sickening rapes and sex attacks.
The Court of Criminal Appeal even increased one of his rape sentences because of "the terrifying amount of violence" he inflicted.
In that case he even forced his victim to sign a note saying she consented to having sex.
Gardai in the north inner city have been notified of Moore's release, amid fears that he may attack again.
A source told the Herald: "This man presents a serious danger to women and he is at large today. There are grave concerns that he could attack again.
"The public need to be made aware that he is back on the streets."
Serial rapist Moore has 11 convictions, and has served a 10-year sentence for rape, a seven-year sentence for another rape, a one-year sentence for an indecent assault and a two-and-a-half-year sentence from the Special Criminal Court.
He is a registered sex offender and is required to notify gardai of his address and if he has any plans to change it.
He was given a five-month sentence yesterday for hitting a woman in the face with a set of keys, but was freed when the sentence was backdated.
Moore admitted the assault.
The court heard that he struck the woman in a dispute in the garden of their apartment complex in 2009.
He had spent nearly a year and a half in prison while waiting for the case to come to court and the judge did not add to the time he had already served.
The Romanian woman in the assault case sustained only minor scratches, but the court heard he went on to claim to gardai that the victim was working as a prostitute.