August 9, 2015
The attack was discovered on Wednesday, and made public on Saturday.
The encrypted credit card details of up to 90,000 people may have been accessed, the mobile phone firm said.
The Information Commissioner’s Office, which examines data breaches, confirmed it was aware of the incident.
Carphone Warehouse says the data could include names, addresses, dates of birth and bank details and it is contacting all those affected.