In a notice posted on the company's official PlayStation website, Sony has acknowledged the possible unauthorised access of personal information on the PlayStation Store.
"Although unlikely, it is possible that the passwords of a small percentage of PlayStation Network users may have been changed through unauthorised access, making it possible to view users' personal information and/or use the wallet for the PlayStation Store," the statement read.
Because PlayStation Network accounts do not display entire credit card numbers, Sony said that any unauthorised access to users' PlayStation Network accounts was very unlikely to have compromised their credit card numbers.
The company said that it has taken immediate measures to rectify this issue and that system security has been restored.
"We have investigated the extent of unauthorized access and possible alteration of passwords that could have occurred before corrective measures were taken, and are directly contacting customers who may have been affected by this incident," the statement continued.
Sony suggests that PlayStation Network users sign in to the service to verify that their account is intact. If users are able to sign in with their pre-set passwords, their accounts have not been affected.