Wendy's says hackers stole customers' credit and debit card information at 1,025 of its restaurants in the United States last year. That number is far bigger than earlier estimates.
More than 5,700 Wendy's restaurants are in the United States.
The Dublin-based hamburger chain says hackers accessed card numbers, names, expiration dates and codes on the cards. They used some customers' cards to make fraudulent purchases at other stores.
In May, Wendy's said malware was found in fewer than 300 restaurants starting in the fall of 2015. About a month later, it said two types of malware were found and the number of restaurants affected was "considerably higher."
Wendy's posted a list of affected restaurants on its website.