A stranger stabbed a 25-year-old woman in an unprovoked Tuesday evening rush hour attack on the staircase of a Manhattan subway station, cops and sources said. 

The victim was walking down the stairs inside the 23rd Street C and E train station in Chelsea around 6:30 p.m. when the maniac plunged what appeared to be a knife into the left side of her back, according to authorities and sources. 

The woman was taken to Bellevue Hospital, where she was listed in stable condition. 

The brute took off after the random violence, cops said. 

He is believed to be Hispanic, 5-foot-7 and was last seen wearing a white shirt and blue sweatpants, police said. 

No arrests had been made by Wednesday afternoon.