Facebook’s European operations are based in Dublin, so it notified the Irish Data Protection Commission that it suffered a breach that put 50 million users at risk. The DPC signaled that it found Facebook’s breach report incomplete. “At present, Facebook is unable to clarify the nature of the breach and risk to users,” the DPC wrote. “We are pressing Facebook to urgently clarify these matters.”

In addition to the obvious exposure of personal information and access to Facebook itself, the breach also puts at risk anyone who ever used Facebook social login, a feature that allows users who are logged into Facebook to automatically log into other sites.

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