Cyber security experts have warned holidaymakers not to post pictures of their boarding passes to social media, because they could be used by thieves to discover private details.
Barcodes found on boarding passes contain a lot of private information, which anyone can access with basic barcode reading software available for free on most smartphones.
The barcodes can include your full name, arrival and departure airports, the airline you're flying with, the flight record number and your frequent flyer number.
Brian Krebs wrote on his cyber security blog Krebs on Security how holidaymakers can protect their private information.
"The next time you’re thinking of throwing away a used boarding pass with a barcode on it, consider tossing the boarding pass into a document shredder instead," he said.
"Two-dimensional barcodes and QR codes can hold a great deal of information and the codes printed on airline boarding passes may allow someone to discover more about you, your future travel plans, and your frequent flyer account."
Once someone has access to an account, they will be able to do anything from cancelling a future flight to changing personal information related to the account, Mr Krebs warned.
He advised holidaymakers to refrain from posting pictures of their boarding passes online and said it's best to shred travel documents after use.
In 2006, a man was able to access personal information from a boarding pass he found in a Heathrow airport bin, The Guardian reported.
By scanning the barcode on the pass, he was able to access information from the traveler's passport number to his date of birth.
With that basic information, a quick internet search led him to find the man's home address, his profession and his academic qualifications.
"It would have been only a short hop to stealing his identity, committing fraud in his name and generally ruining his life," the man said.