This is being offer for sale on the bay right now with the following description:
Up for grabs is the autographs by the legendary Nirvana featuring the late Kurt Cobain. The fully signed promotional only 8x10 photograph was autographed on December 31, 1993 at the Oakland Coliseum in Oakland, California, a little over a year later Kurt would be dead. Photograph not available to the public, sent to me thru DGC publicity department when i worked for a fanzine, all autographs are still crisp from the black sharpie used at the time, item over 20 years old!
Very rarely do fully autographed Nirvana items come on sale on ebay, not priced to sell but priceless none the less?

The seller claimed that it was obtained in-person backstage after the concert. The 1st red flag on this piece is that if it was signed on December 31, 1993, Krist Novoselic would have signed Krist instead of Chris in 1993. Krist is his original Croatian spelling of his name. He signed his name Chris before 1993 but not after 1993.