Social media giant Facebook, Inc. (NASDAQ: FB) is making headlines for another privacy scandal, according to cybercrime investigative journalist Brian Krebs.

What Happened

Facebook employees had easy access to hundreds of millions of Facebook users that were stored in "plain text," Krebs wrote in his Krebs on Security blog. The latest revelations come from an unnamed senior Facebook employee who said 200 million to 600 million users' passwords could have been accessed by 20,000 Facebook employees.

The source said the company is still investigating how many passwords were actually exposed in a security breach which may date back to 2012, Krebs wrote.

Why It's Important

At first glance, storing user passwords on internal Facebook databases may not seem that concerning. But Krebs wrote his source said 2,000 engineers or developers combined for 9 million queries for data that include unencrypted passwords.

A Facebook software engineer Scott Renfro told Krebs the company isn't ready to talk about any specific numbers. The company's VP Engineering, Security and Privacy Pedro Canahuati wrote in a blog post it identified the issue as part of a "routine security review" in January.

"To be clear, these passwords were never visible to anyone outside of Facebook and we have found no evidence to date that anyone internally abused or improperly accessed them. We estimate that we will notify hundreds of millions of Facebook Lite users, tens of millions of other Facebook users, and tens of thousands of Instagram users. Facebook Lite is a version of Facebook predominantly used by people in regions with lower connectivity."

Renfro also said the company has a "bunch of controls in place" to mitigate privacy-related problems and it's in the process of "investigating long-term infrastructure changes."

Facebook's stock traded lower by 1 percent Thursday afternoon to $164.19 per share.

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