About 143 million US customers of credit report giant Equifax may have had information compromised in a cyber security breach, the company has disclosed.
Equifax said cyber-criminals accessed data such as Social Security numbers, birth dates and addresses during the incident.
Some UK and Canadian customers were also affected.
The firm’s core consumer and commercial credit databases were not accessed.
Equifax said hackers accessed the information between mid-May and the end of July, when the company discovered the breach.
Malicious hackers won access to its systems by exploiting a “website application vulnerability”, it said but provided no further details.
The hackers accessed credit card numbers for about 209,000 consumers, among other information.