Thanks to mobile check-in and airline apps, many travelers are no longer carrying printed boarding passes through the airport. In the case that you get an urge to take that Instagram-worthy boarding pass photo, you might want to rethink it.

Boarding passes are packed with information about your flight, but the host of numbers and letters printed on the rectangular piece of paper mean more than we think.

Each of the number groups on your pass gives the airline important information about you that you’ve shared throughout your purchase and relationship with the airline. There is also a six-digit code on your boarding pass that is especially important to keep out of the hands of those who’d use your personal information to their advantage.

Noam Rotem, a security researcher, discovered a discrepancy in an online booking system called Amadeus. The booking system is used by over 200 major airlines, travel agencies, and third-party booking sites. The hole in the system that Rotem found could potentially give hackers the opportunity to gather a person’s data using the six-character code printed on a boarding pass. Rotem told Popular Mechanics, “Just by guessing PNRs I was able to access personal data and change contact details of customers.”

Not only could hackers change personal details in your profile, but Safety Detective says they could even cancel flight reservations and steal frequent flier miles.

The good news is Amadeus has come up with a solution to the PNR glitch, but even with the glitch handled, hackers are always looking for ways to get a hold of personal information. Travelers should still keep their boarding passes protected. “Keep that six-digit code as secret and safe as you would your credit card or Social Security card number,” Rotem said.