Danny Devon suffered fractures to his jaw, cheek and eye socket in the assault that happened on October 31 Hampton Hargate.
Yesterday police arrested three boys - one aged 14 and two aged 16 - on suspicion of assault occasioning grievous bodily harm (GBH)
All three have now been bailed by police.
The attack happened at 5.44pm on Sunday, October 31 at Hargate Hill off Hargate Way.
Following the attack, DS Tom Power, from Cambridgeshire police, said: “This was a violent attack which left a young boy seriously injured and needing hospital treatment.
“We are taking this incident very seriously and would like to reassure people that we are conducting neighbourhood patrols of the area.
“We believe there were a number of people in the area at the time of the assault and we strongly urge those people, or anyone with any information about the attack, to come forward.”
The investigation continues and anyone with any information is urged to contact police via the web chat service https://bit.ly/3vsiYDw or online forms at www.cambs.police.uk/report quoting crime reference 35/74805/21.