They say the 26-year-old was attacked around 10.45 pm on Saturday in the main dance tent at the XFest in the town’s Lorimer Park.
He was later taken 28 miles to Dumfries and Galloway Royal Infirmary where he was treated for a serious back injury.
Police Scotland has issued an appeal for any witnesses to come forward.
A spokesman said: “The tent at the time contained around 200 people and anyone who may have witnessed this assault is asked to call police at Sanquhar on telephone number 101.”
NEWSDESK: 01461-202417
