The attack took place sometime between midnight and 1 a.m. on Thursday, according to a U.S. Air Force spokeswoman, who declined to release more information.
Local television station KCRA reported that Stone, during a fight in the street near several popular bars in the mid-town section of Sacramento, was stabbed multiple times in the torso.
It was not immediately clear if anyone had been arrested in connection with the stabbing. Reuters could not immediately reach Sacramento police for comment.
Stone and two friends, Anthony Sadler and Alek Skarlatos, subdued a gunman on a high-speed train bound for Paris in August, winning accolades from the presidents of France and the United States.
Stone, Sadler and Skarlatos, who grew up together in the Sacramento area, were honored in a parade through California’s capital city last month.