Those footsteps you hear are the sound of some hacker or identity thief potentially making off with your personal information.
MasterCard says it's investigating a possible security breach related to a third-party vendor and has alerted banks and law enforcement officials. Some reports identify the vendor as Global Payments, which processes credit-card transactions.
As many as 50,000 MasterCard and Visa cardholders may be at risk, according to some accounts of the breach. Others say a "massive" amount of consumer data may be threatened, perhaps involving millions of people.
"MasterCard is concerned whenever there is any possibility that cardholders could be inconvenienced and we continue to both monitor this event and take steps to safeguard account information," the company says. "If cardholders have any concerns about their individual accounts, they should contact their issuing financial institution."