The bookstore says customers at 63 stores nationwide may have had their accounts compromised.
Barnes & Noble says hackers broke into the keypads in front of cash registers where customers swipe their credit cards and enter their four-digit PINs, personal identification numbers.
The New York Times reports that the company discovered the security breach around September 14. But sources tell the Times that the Justice Department asked Barnes & Noble to keep the matter quiet, so the FBI could figure out who was behind it. After getting word of the tampering, the bookstore chain disconnected all PIN pads from its stores nationwide.
Customers looking to use a credit card will simply have their cards swiped on the reader attached to the cash register.