NEW YORK (AP) — Millions of passwords, credit card numbers and other personal information may be at risk as a result of a major breakdown in Internet security revealed earlier this week.

The damage caused by the “Heartbleed” bug is currently unknown. The security hole exists on a vast number of the Internet’s Web servers and went undetected for more than two years. While it’s conceivable that the flaw was never discovered by hackers, it’s nearly impossible to tell.