A bug that lets you execute code on Facebook's servers is worth millions if not billions of dollars. You'll be rewarded with much less than that, but considering Facebook's market cap it is extraordinarily valuable.
There are no legal entities that would buy the bug, the USG can access any data w/ a warrant (thats free) vs. "millions or billions". Any other law enforcement agency could do the same thing. There is really no value there to them. So it would have to be blackhats, and that means some idiotic Russians mass owning everyone with old Java bugs. Again - not worth much.
This sort of bug has very little value, except to facebook.