Your boarding pass contains far, far more information than you might think.
It doesn't just display your name and where you're flying, but gives people access to highly confidential information, as well as providing the ability to modify or cancel your booking.
Just how easy is it to gain access to someone's information?
Steve Hui, CEO of iflyflat.com.au, which specialises in optimising frequent flyer points set out to find out.
"I come across posts every day: pictures in which people show off a flashy boarding pass emblazoning their name and destination. Some may even be flying first or business class, so they want to share the excitement."
Some very key pieces of information are printed on most boarding cards: your name, your ticket number or booking reference and a barcode.
Hui decided to investigate how much information could be accessed using an image posted by an Australian Virgin Australia passenger, who was flying co-share on Delta Airlines.
Delta publishes an astonishing amount of information, including the E-Ticket number, booking reference, frequent flyer number and even how many bags you have checked in. Hui decided to test just how vulnerable the system was, and headed to the Delta website.
Under "Manage My Booking" all he needed was a passenger name and an E-Ticket number or booking reference.
As all that was on the boarding card, so he was quickly able to log into the booking and see all the passenger's details.
He could view the passenger's entire itinerary, and see when and where they were going to travel.
Details also included their seat numbers, frequent flyer details and ticket numbers.
Taking it even further, it was easy to see a full breakdown of the fare paid, including the date of purchase and the last four digits of the credit card used.
"People with malicious minds could use that information to potentially cancel or change your flights, change your seat or cause other issues," Hui said.
Beware: The barcode hides even more information
Even scarier is what can come up on a barcode.
In another social media photo, the passenger has tried to cover up the important information, hiding her full name but leaving the barcode in full view.
The barcode contains basically all the information on the boarding pass, stored in a specially readable format.
"You may think that airport computers are the only devices that can read this, but the truth is, anyone can read a barcode," says Hui. "There are dozens of online barcode readers that provide information based on a photo you upload."
Hui was able to retrieve all the passenger's details without seeing the rest of the boarding card.
The text provided full name, flight number, route, booking reference, ticket number, frequent flyer number and more.
Accessing all this information is a lot easier than you may have thought, and there is a great risk associated with publishing uncensored images of boarding passes.
Not only can these details be used for identity theft purposes, but you can suffer major financial loss if someone were to use this method to take control of a frequent flyer account.
Identity theft is real
This doesn't mean you shouldn't post images of boarding passes at all — if you want to show off that hard-earned business or first class ticket to the world, just be sure to cover up or blur out any vital information.
A much safer idea is to share pictures of you drinking champagne in the lounge or on board the plane.
Says Hui: "It's much more than just a boarding card, so be smarter and please take care."