Millions of customers affected by the Equifax Cyber Incident.

Equifax said hackers accessed the information in their base between mid-May and July. The criminals accessed datas such as Social Security numbers, birth dates and addresses but the good news is the firm’s core consumer and commercial credit databases were not touched.

The hackers accessed credit card numbers for about 209,000 consumers, among other information.

Equifax chief executive Richard Smith said the incident was "disappointing" and "one that strikes at the heart of who we are and what we do".

"I apologise to consumers and our business customers for the concern and frustration this causes," said chairman and chief executive Richard F Smith.

"We pride ourselves on being a leader in managing and protecting data, and we are conducting a thorough review of our overall security operations."

Equifax is one of three nationwide credit-reporting companies that track and rate the financial history of U.S. consumers. It gets its data -- without you even knowing -- from credit card companies, banks, retailers, and lenders.

Equifax will not be contacting everyone who was affected, but will send direct mail notices to those whose credit card numbers or dispute records were accessed.