Visa, Mastercard Warn of Security Breach (V, MA)

US credit card giants Visa Inc. (NYSE: V) and Mastercard Inc. (NYSE: MA) have reported possible security breaches to law enforcement officials and card-issuing banks. A report on the KrebsonSecurity blog cites sources as saying the breach is “massive” and may affect more than 10 million card numbers.

From the Krebson blog:

In separate non-public alerts sent late last week, VISA and MasterCard began warning banks about specific cards that may have been compromised. The card associations stated that the breached credit card processor was compromised between Jan. 21, 2012 and Feb. 25, 2012. The alerts also said that full Track 1 and Track 2 data was taken – meaning that the information could be used to counterfeit new cards.

The breach is reported to have occurred at an unnamed credit card processing company or companies. Mastercard told the WSJ that its own systems have not been affected.