Data breach may have involved millions of patients, Kaiser says. What was leaked?

A data breach may have exposed data on millions of Kaiser Permanente patients, the California-based health care chain reported.

Kaiser is notifying 13.4 million current and former patients about the breach, it said in a statement to McClatchy News. The health care chain is based in Oakland, California.

Online software may have inadvertently sent data to third-party vendors such as Google, Microsoft Bing and X, formerly known as Twitter, the company said.

The data was related to IP addresses, names and information on when patients signed onto accounts or how they navigated through Kaiser websites, the statement said.

“No usernames, passwords, Social Security numbers, financial account information or credit card numbers were included in the transmission to these third parties,” Kaiser said.

The company has removed the software involved in the breach from its sites and continues to investigate the issue, the statement said.

Kaiser is not aware of any misuse of the data but is notifying patients “out of an abundance of caution,” the company said.

Kaiser Permanente has 40 hospitals and 618 medical facilities in California, Colorado, the District of Columbia, Georgia, Hawaii, Maryland, Oregon, Virginia and Washington, according to its site.