The producers of a privacy app for cell phones say that Facebook has a big problem on their hands right now, and they didn't even know it.

Yahoo reports that a major Facebook bug that makes millions of users vulnerable to identify theft from hackers. The CEO of MyPermissions, a privacy app on devices, says that:

Any application that uses Facebook to connect can be shut down. Think about it like this: You download an app that promises to do one thing, but actually comes from a hacker who wants to seriously invade your privacy by mining your data. Given the right coding, this developer could trigger the same effect, basically making it impossible for a user to disconnect this malware app and revoke its permission to access your personal information.

What does this mean? Remember, when you download an app, you basically agree to share your personal information with it, so you are taking some level of risk -- like entering your credit card information or other personal info on any number of retail sites.

The good news: Facebook has taken action, and the bug should be fixed soon.