User blog comment:Jimeee/Skyrim 1.9 beta update adds Legendary difficulty and raises level cap (Updated Apr 8th)/@comment-174.25.111.134-20130309213625/@comment-71.218.149.111-20130310022551

The secret chest is not a glitch or exploit. It is simply the location of the caravans items. Every shop has one of these, it is just impossible to find or incredibly hard to locate, much less open.