NEW YORK (CNN/Money) - A security breach has occurred at a third-party processor of payment card transactions that affects over 40 million card accounts, Mastercard International said Friday.
Of the cards involved, 13.9 million were MasterCard-branded cards, which include Maestro and Cirrus, and 22 million were Visa cards, said Visa spokeswoman Rhonda Bentz.
The breach took place at the Tucson office of CardSystems Solutions, which processes transactions on behalf of financial institutions and merchants. CardSystems said in a statement that it identified the breach on May 22 and contacted . . .