McDonald's is the latest big company to be hit by a data breach that has exposed customers' details.
The world's biggest burger chain said cyber attackers had accessed a "small number" of files on customers in South Korea and Taiwan.
The breach included e-mail, delivery addresses and phone numbers - but not payment details.
A spokeswoman for the firm said it would take steps to "notify regulators and customers listed in these files".
The details of the breach, first reported by the Wall Street Journal, were discovered during an external investigation after unauthorised activity was spotted on the company's network.
Credit: BBC News