Bragging about your upcoming trip online might seem harmless, but snapping a photo of your boarding pass is a definite don’t. Sure, your followers already know your name—and they might even know your destination—but according to Brian Krebs, author and founder of Krebsonsecurity.com, which specializes in investigative stories on cyber crime and computer security, other personal data is at risk. Your frequent flyer card and passenger name record (PNR) could be jeopardized with a social post. With a little finagling, hackers can access your earned miles, phone number, date of birth, and even passport data. Based on your booking number, criminals can also find out when you leave and return. Knowing that no one is home could entice burglars to break in while you’re away.