The Palo Alto-based company says the fault rested with developers whose games are played on the Facebook site. Facebook said in a press statement that it is planning a new system to "dramatically limit the sharing of user IDs."
It also said that, "there is no evidence that any personal information was misused or even collected as a result of this issue." Facebook turned down a request for an on-camera interview.
CNET senior editor Natali Del Conte says the more advertisers know about an online user's location, gender, preferences and interests, the more easily they can deliver targeted ads to match those criteria.
"How long has this been going going on, did they know it and when did they know it? And if they didn't know it, why didn't they know it?" she said.
One San Francisco game operator, Lolapps, apparently was suspended from Facebook for a time over the weekend because it had violated Facebook's privacy guidelines. Lolapps was scheduled to do an interview with ABC7 News at its offices on New Montgomery Street, but then it cancelled without explanation.
The Wall Street Journal reported that personal data was shared with 25 advertisers and tracking services. The Journal said that the popular game Farmville, made by San Francisco's Zynga, was among the applications involved.
"I want to be able to trust when I'm on Facebook and I think I'm just talking to my friends on Facebook that that's only where the information is going," Palo Alto resident Nita Gibson said.
When ABC7 News logged onto Facebook on Monday afternoon to play a game made by Zynga, a dialogue box appeared requesting permission to access the user's basic information.
That information included name, profile picture, gender, networks, user ID, list of friends and "any other information I've shared with everyone." There is a choice of two buttons: Allow or Leave Application.
The non-profit group Common Sense Media, based in San Francisco, urged that new laws be enacted to protect the identity and other personal details of minors.
Founder and CEO James Steyer said that issues such as the one involving Facebook creates a Big Brother scenario in which captured and shared data will track people "from cradle to grave" with no ability to opt-out.
Steyer cited a study that Common Sense Media released last week in Washington, D.C. that says 85 percent of parents surveyed are more concerned about online privacy than they were five years ago.
He added that this latest incident should lead to new laws so minors aren't tracked.
"They will be able to target them from cradle to grave, if you will, and know stuff about them and share it with others that's simply inappropriate. So we actually believe there should be a 'Do Not Track' kids' law in the United States, similar to the 'Do Not Call' registry," Steyer said.
There is a lot of user data generated by Facebook's 500 million users and an estimated 70 percent of them play games on the site.