Target on Thursday confirmed that it was hacked in a breach that could affect approximately 40 million credit and debit card customers.

Target said the breach, first reported by Brian Krebs, affects those who used credit or debit cards in U.S. stores between Nov. 27 to Dec. 15.

"We have determined that the information involved in this incident included customer name, credit or debit card number, and the card's expiration date and CVV (the three-digit security code)," the store said.

The retailer has since "identified and resolved" the problem. It has alerted affected financial institutions and is "partnering with a leading third-party forensics firm to conduct a thorough investigation of the incident."

"Target's first priority is preserving the trust of our guests and we have moved swiftly to address this issue, so guests can shop with confidence. We regret any inconvenience this may cause," Gregg Steinhafel, chairman, president and CEO of Target, said in a statement. "We take this matter very seriously and are working with law enforcement to bring those responsible to justice."

According to Krebs, the scam involved "the theft of data stored on the magnetic stripe of cards used at the stores." Initially, he said, officials thought the breach affected accounts from Thanksgiving to Dec. 6, but that was later extended to Dec. 15.

Target said those who suspect their accounts were impacted by the breach should call 866-852-8680. It also urged customers to "remain vigilant for incidents of fraud and identity theft by regularly reviewing your account statements and monitoring free credit reports." A notice on its website includes information on checking credit scores, as well as specific information for residents of Iowa, North Carolina, and Massaschusetts.

UPDATE: Visa said in a statement that it offers cardholders zero liability. "Because of advanced fraud-monitoring capabilities, the incidence of fraud involving compromised accounts is actually rare, and Visa fraud rates remain near historic lows," the company said. "As always, Visa encourages cardholders to regularly monitor their accounts, carefully review statements and notify their issuing financial institution promptly of any unusual activity."

For more, check out PCMag Live in the video below, which discusses the Target breach, as well as What To Expect After the Target Card Data Breach.