When you hack something, even with good intents, you always end exposing yourself to some form of retorsion.

You can point your fingers to vulnerabilities every day full time just to make the web a better place and many will thank you for this but much more will just threaten you or file a complaint.

This is one of the main motivation behind the no more free bugs movement: http://blog.trailofbits.com/2009/03/22/no-more-free-bugs/