The US credit card issuer said it identified the hacking July 19 and the person responsible has been arrested by the Federal Bureau of Investigation.
The incident is expected to cost between $ 100 million and $ 150 million in 2019, mainly due to customer alerts, credit monitoring and legal support, Capital One said.
The hacker was unable to access credit card account numbers, but around 140,000 social security numbers and 80,000 associated bank account numbers were compromised, Capital One said.
About 1 million social insurance numbers of the company's Canadian credit card customers were also compromised.
The hacker was able to "exploit" a configuration ation vulnerability & # 39; s in the company's infrastructure, it said, and added that the vulnerability was reported to Capital One by an external researcher.
(Reporting by Uday Sampath in Bengaluru; Editing by Sandra Maler and Sonya Hepinstall)