Oct 21, 2010 09:31 GMT  ·  By

The House of Representatives Committee on Energy and Commerce sent a letter to Facebook asking for answers regarding a privacy breach uncovered recently, that involved numerous applications leaking user information to third parties.

The letter [pdf] was sent on Monday, following a Wall Street Journal investigation, which exposed the sharing of user IDs (UIDs) between Facebook developers and their advertising partners.

It is addressed to Facebook's CEO Mark Zuckerberg and is signed by Congressmen Edward J. Markey, co-chairman of the Bi-Partisan Privacy Caucus, and Joe Barton, ranking member of the Committee on Energy and Commerce.

The eighteen questions contained within are related to this particular incident, as well as past ones. Amongst other things the company is asked to reveal its app review procedures.

"What procedures do you have in place to detect and/or prevent third party applications that may breach the terms of Facebook's privacy policy?" one question reads.

This has probably been on everyone's mind, because Facebook hosts around 550,000 applications and reviewing them periodically for policy violations is bound to be challenging.

The congressmen also ask if similar breaches have happened in the past and if yes what measures have been put in place as a result.

Earlier this year, following a website upgrade, Facebook started leaking user IDs via referrer URLs to advertisers. The breach lasted from February to May.

A lawsuit seeking class-actions status was filed against the company last week in California Northern District Court because of the incident.

Facebook is asked to identify how many users were affected in the latest case, what data has been exposed, how many applications violated its privacy policy, what are the exact breached terms, and what changes the company plans to make.

User IDs are unique identifiers that can be used to easily access the profiles of particular users. Even with the highest privacy settings in place, a Facebook profile will still display a user's real name and picture.

In its report, the Wall Street Journal states that in addition to the UIDs, some applications also shared information about users' friends.

Mark Zuckerberg is respectfully asked to respond to the letter by October 27, 2010, and the submitted information will be used in discussions regarding pending privacy legislation.