A 23-year-old woman was allegedly assaulted at the Music Barn, High Street, Cranford, in the early hours of Sunday morning.
The woman was at a charity music event when she was assaulted by two people, one of whom is alleged to have had a knife.
The incident happened shortly after midnight on Sunday, August 30, and police would like to speak to anyone who may have been at the event.
A 27-year-old woman and a 30-year-old man have been arrested in connection with incident and bailed.
The victim received minor injuries.