The owner of Dixons and Carphone Warehouse today revealed hackers grabbed the details of 5.9million customers cards and 1.2million personal records.
The Dixons Carphone share price fell by 5.5% within minutes of major hack announcement.
About 5.8 million cards affected had chip-and-PIN protection, the company said, and the data accessed for these cards do not include the personal identification codes or other authentication data enabling cardholders to be identified or purchases to be made.
"We've taken action to close off this unauthorised access and though we have now no evidence of fraud as a result of these incidents, we are taking this extremely seriously".
Dixons Carphone chief executive Alex Baldock said: 'We are extremely disappointed and sorry for any upset this may cause.
The group said it had informed the Information Commissioner's Office (ICO), the Financial Conduct Authority (FCA) and the police about the incident. In the 2015 incident, hackers exposed the personal details of more than 3 million customers and some employees.
Dixons Carphone says the hack began in July a year ago, so if you purchased anything or used their services since summer 2017, you may have been caught up.
Dixons Carphone said it had immediately notified the relevant card companies so that they could protect customers.
Only 105,000 non-EU issued payment cards are at risk as they aren't chip and PIN protected, meaning they could be cloned. "We've taken action to close off this unauthorized access and though we have now no evidence of fraud as a result of these incidents, we are taking this extremely seriously". "As a multinational organisation, Dixons Carphone would have been well aware of the Target breach".
It comes after telecoms firm TalkTalk was hit by a major cyber attack in October 2015, which saw the personal data of almost 160,000 people accessed by hackers and left the firm facing a record £400,000 fine for security failings.
"The protection of our data has to be at the heart of our business, and we've fallen short here", he said. The possibility of phishing attempts using this information is a good one, and people could be caught off-guard if they can't remember buying something from Dixons Carphone in the first place.
Why Angelina Jolie Could Lose Custody of Her Kids to Brad Pitt
The court, however, is letting 16-year-old Maddox essentially decide how much time he wants to spend with Brad because he's older. While in Pitt's care, Jolie is only allowed to call the children one time per day and at a time agreed upon by both parents.