An analytics tool called "App Events" allows app developers to record user activity and report it back to Facebook, even if the user isn't on Facebook, according to the report .
One example detailed by the Journal shows how a woman would track her period and ovulation using an app from Flo Health. After she enters when she last had her period, Facebook software in the app would send along data, such as whether the user may be ovulating. The Journal's testing found that the data was sent with an advertising ID that can be matched to a device or profile.
Although Facebook's terms instruct app developers not to send such sensitive information, Facebook appeared to be accepting such data without telling the developers to stop. Developers are able to use such data to target their own users while on Facebook.
Facebook said in a statement that it requires apps to tell users what information is shared with Facebook and it "prohibits app developers from sending us sensitive data." The company said it works to remove information that developers should not have sent to Facebook.
The development comes as Facebook is dealing with increased scrutiny over how it handles user data. Last week, British lawmakers issued a scathing report calling for tougher privacy rules for Facebook and other tech firms.
The data-sharing is related to a data analytics tool that Facebook offers developers. The tool lets developers see statistics about their users and target them with Facebook ads.
Besides Flo Health, the Journal found that Instant Heart Rate: HR Monitor and real-estate app Realtor.com were also sending app data to Facebook. The Journal found that the apps did not provide users any way to stop the data-sharing.
Flo Health said in an emailed statement that using analytical systems is a "common practice" for all app developers and that it uses Facebook analytics for "internal analytics purposes only." But the company plans to audit its analytics tools to be "as proactive as possible" on privacy concerns.
Hours after the Journal story was published, New York Gov. Andrew Cuomo directed the state's Department of State and Department of Financial Services to "immediately investigate" what he calls a clear invasion of consumer privacy. The Democrat also urged federal regulators to step in to end the practice.
Securosis CEO Rich Mogull said that while it is not good for Facebook to have yet another data privacy flap in the headlines, "In this case it looks like the main violators were the companies that wrote those applications," he said. "Facebook in this case is more the enabler than the bad actor."