The incident occurred after 8:00 p.m. on Sierpnia '80 Street in Bolesławiec during the Ceramic Festival.
The 24-year-old man was attacked and beaten. He suffered fractures to the bones of the skull and facial skeleton, as well as injuries to the eyelid and eye socket.
He was at the emergency department during the night and will require further treatment.
It is not known whether security intervened at all. The head of the cultural center that organized the festival is not answering the phone.
This was the second attack during the festival. In the first, football hooligans attacked a woman near the former police station, also on Sierpnia '80 Street.