A June update to the Skype software adds recipients to some of the instant messages you send out through the system. Instead of just sending it out to the person or people selected for the message, it includes other people as well without your knowledge.
According to VentureBeat, Skype knows all about it:
“We are aware that in rare circumstances IMs between two contacts could be sent to an unintended third contact. We are rolling out a fix for this issue in the next few days and will notify our users to download an updated version of Skype.”
Be careful what you say and who you’re saying it about when Skyping. You might end up saying the wrong thing to the wrong people.
Microsoft purchased Skype last year.