British Airways has been hacked, compromising the card details of hundreds of thousands of customers who used its website and app over a two-week period.
Alex Cruz, BA's boss says that the website suffered a "sophisticated, malicious criminal attack".
The breach has affected bookings made between 21 August and 5 September, with around 380,000 card payments compromised.
The hackers gained access to names, street and email addresses, credit card numbers, expiry dates and CVV codes - enough to use cards.
BA is telling customers who made bookings during the affected period to contact their bank or card provider and is promising that it will not leave anyone out of pocket.