Facebook stored “hundreds of millions” of passwords in plaintext, unprotected by any encryption, the company has admitted, Gazeta reported quoting  CNBC.

It was noted that as part of a routine security review in January, Facebook found that some user passwords were being stored in a readable format within our internal data storage systems.

The 600 million users represents a significant portion of Facebook's user base of 2.7 billion people. 

Affected users will be directly notified.