At about 2.30am, the victim, a man in his twenties, was injured after a fight.
He was taken to hospital where he remains for treatment.
Investigating officer DS Tracey Benham, based in Aylesbury said: “This incident happened in public and I’d like to appeal to anyone who may have witnessed the altercation to get in touch.
“Similarly, if you have any information that may help our investigation, please call the 24-hour Thames Valley Police enquiry centre on 101.”
Alternatively, you can contact Crimestoppers anonymously on 0800 555 111.