Korean Air and Asiana Airlines say Amadeus IT Group, which runs reservation and ticketing systems for many airlines, notified them on the night of Oct 20 (KST) of a suspected leak of customer data from its systems. Korean Air's notice to customers says the cause was unauthorized access using login credentials assigned to an account in Amadeus's system, sometime between August 2023 and September 2026, with the exact timing still under investigation.

• Korean Air: booking reference numbers are confirmed among the exposed data; other data types are still being checked with Amadeus. It found no sign of intrusion into its own systems and has emailed affected customers.
• Asiana: reservation information was exposed; payment data was not, because payments run on a separate system.
• Amadeus: the airlines say it has blocked the access and turned on dark-web monitoring. Neither the number of affected customers nor whether other carriers are involved has been disclosed.

A booking reference plus a surname is often enough to open and change a booking online, so watch for unexpected changes and for phishing that cites a real itinerary.