A critical flaw in Apple’s FaceTime video chat service allows someone to listen through another user’s iPhone even if that person did not answer the call, a report said on Monday.

The apparent defect can be exploited by placing a call through the FaceTime app and then using the menu option to add yourself to the call, according to CNBC.

After the “add person” option is selected the caller can then listen through the other person’s phone before they answer the call.

The person being called is given an option to answer but is not alerted that the caller can hear them.

In addition, if the person being called hits the power button the call automatically transfers to video — which means the video camera automatically turns on.

Apple told CNBC that they were working on a fix to the problem.

“We’re aware of this issue and we have identified a fix that will be released in a software update later this week,” a spokesperson said.

This story originally appeared in The New York Post.