The victim, a man in his 30s, was sitting at a table at a pub on White Horse Lane on Wednesday 13 July between 11.10pm and 11.30pm when he was approached by two men.
A verbal altercation took place and the victim was assaulted and suffered multiple head injuries.
Following the incident, two 18-year-old Canterbury men were arrested on suspicion of assault and possession with intent to supply. They were released on bail while the investigation is ongoing.
Officers want to speak with anyone who saw or heard anything suspicious during the attack.
Witnesses should contact Kent Police at 01843 222289 and reference case number 46/135151/22.
You can also call Crimestoppers anonymously on 0800 555111 or fill out an online form at www.crimestoppers-uk.org.