The bug was triggered when callers added themselves to the same call to start a group chat, making FaceTime believe the receiver had accepted the call.Original article
Once the bug was discovered and published on tech blogs, Apple disabled the group chat function and said a fix would be released in a software update later this week.
While Balasubramonian believes Apples bug was not a malicious one , the average user is at the mercy of both the competency and honesty of the app or device developers.
Make sure you update your software regularly because people are finding these in the background, and fixes are being done on a weekly basis.