Many Facebook applications share users' personal information with advertising networks and other Internet-tracking companies, according to a Wall Street Journal report.

Facebook said Sunday, however, that the Journal is exaggerating the problem and that Facebook is working to put an end to any inadvertent data sharing.

The problem affects tens of millions of Facebook's 500 million users, the Journal said, and all of the social-networking site's top 10 apps. That includes Zynga's FarmVille, Texas HoldEm Poker, FrontierVille, Café World, Mafia Wars, and Treasure Isle. Also in the top 10 were Phrases, Causes, Quiz Planet, and iHeart.

Zynga did not immediately respond to a request for comment. A Sunday note on the "Phrases" Facebook page said that Facebook disabled the game "without talking to us about any problems that we could address."

At issue are Facebook user IDs (UID), a number that is assigned to every Facebook user that can be used to look up your name, the Journal said. It might also reveal age, location, occupation, and photos, depending on your privacy settings.

Facebook, however, denied that it was sharing personal data.

"No one can access private user information without explicit user consent," Mike Vernal, a Facebook engineer, wrote in a blog post.

Developers are not allowed to disclose personal information to ad networks and data brokers, and Facebook suspends or disables the accounts of those who do it, he said.

"In most cases, developers did not intend to pass this information, but did so because of the technical details of how browsers work," Vernal wrote.

As a result, "press reports have exaggerated the implications of sharing a UID," he continued. Having a UID does not mean private information is made public. "Nevertheless, we are committed to ensuring that even the inadvertent passing of UIDs is prevented and all applications are in compliance with our policy," he wrote.

The news comes five months after sites like Facebook and MySpace fixed a glitch that allowed advertising partners to see user ID information. Specifically, advertising partners might receive user names or ID numbers tied to member's personal profiles if that member clicked on an ad within Facebook or MySpace.

Vernal referenced the May UID incident, but said the technical challenges with the most recent problem "are greater."

"We are talking with our key partners and the broader Web community about possible solutions. We will have more details over the course of the next few days," he concluded.