Customers who shopped at 63 Barnes and Nobles stores across in nine states across the country may have had their credit or debit card information stolen.
Barnes and Noble says it detected tampering with one of the PIN pad devices at each of the stores, and now the FBI is investigating.
Barnes and Noble says the thieves were able to plant bugs in the PIN pads, then pull all the credit card and PIN numbers from the machine. Several of the stores were in Florida, though none were in the northeast part of the state.
Security experts say there are things customers can do to protect themselves.
Jennifer Peery-Salgado was relieved to hear none of the stores were in northeast Florida, but says she still has her guard up.
"It concerns me a little bit, but I think as the holiday season goes on, we're going to see more of this happening," said Jennifer Peery-Salgado, who shops at the bookstore. "It makes me just a little bit more cautious just using credit cards at ATMs and certain machines, but not primarily at Barnes and Noble. I have no issues with it right now."
Barnes and Noble said that last month it disconnected all the faulty PIN pads, which made up less than 1 percent of its pads. The company said it noticed "tampering," which the FBI is now investigating.
Phillip Graves, a cyber security expert at Antisyn IT Services, explains.
"My guess is that they either replaced it with a different PIN pad that they'd already pre-programmed, or they attached something to the PIN pad," Graves said. "So either one of those situations would only take a minute to do."
Barnes and Noble is advising customers who may have swiped their cards in the 63 stores affected to change their debit card PIN numbers and check bank statements.
Channel 4 crime and safety analyst Ken Jefferson advises shoppers to use credit cards instead of debit cards when possible because there are more safety methods in place and they don't have to give out a PIN number.
"You can actually use a debit card as a credit card because it asks the question, 'Is this a credit or a debit?' And if you press credit, you're not compromising your PIN whatsoever," Jefferson said.
It's a change some shoppers are now thinking about making.
"It's kind of scary to buy things because it's so much easier to use a debit card and not carrying cash, but it is scary sometimes," said Choi Fyfe, who shops at Barnes and Noble.
For a list of stores affected by the tampering, click here.