A security bug on Facebook accidentally exposed the personal information (emails or phone numbers) of upwards of 6 million users.
Facebook announced the discovered bug on Friday, noting that its team fixed it within 24 hours upon being made aware of its existence.
In a blog post addressing the issue, Facebook explained:
Facebook also noted, while speaking to Techcrunch, that the security hole has been live since 2012, but made sure to clarify that it hadn't been used in a malicious manner by anyone. Incidentally, and while on the topic of security and privacy, Facebook this week updated its iOS app with new privacy features.
We recently received a report to our White Hat program regarding a bug that may have allowed some of a person's contact information (email or phone number) to be accessed by people who either had some contact information about that person or some connection to them.
Because of the bug, some of the information used to make friend recommendations and reduce the number of invitations we send was inadvertently stored in association with people's contact information as part of their account on Facebook. As a result, if a person went to download an archive of their Facebook account through our Download Your Information (DYI) tool, they may have been provided with additional email addresses or telephone numbers for their contacts or people with whom they have some connection. This contact information was provided by other people on Facebook and was not necessarily accurate, but was inadvertently included with the contacts of the person using the DYI tool.