Careful what you say about the boss, your spouse, or anyone else who may be a Skype contact. A four-week-old bug in the popular Voice Over IP application is sending copies of some messages to unintended recipients, Microsoft officials have confirmed.

The privacy problem was first reported on a Skype support forum by a user who couldn't figure out why some of her contacts were receiving messages she had only authorized to be sent only to select other contacts. Other discussion participants soon chimed in to say they were experiencing the same thing.

According to a statement posted on Engadget, Microsoft officials recently confirmed the glitch.

"We are aware that in rare circumstances IMs between two contacts could be sent to an unintended third contact," the statement read. "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."

The errant messaging behavior was reportedly introduced in an update released on June 21. It's unclear what Microsoft means by "rare."

Update

Skype officials have now posted a blog post identifying vulnerable versions as Skype 5.9 and 5.10 for Windows, Skype 5.8 for Mac, Skype 4.0 for Linux, Skype 1.2 for Windows Phone, Skype 2.8 for Android, and Skype 4.0 for iOS.

"This issue occurs only when a user's Skype client crashes during a Skype IM session, which may in some cases result in the last IM entered or sent prior to the crash being delivered to a different IM contact after the Skype client is rebooted or logged in as a new user," the post stated. "Although we cannot determine precisely how many users may have been affected by this error, we believe the number is small given the very specific circumstances under which the error occurs. At Skype, our customer experience is paramount and we are working hard to release fixes for impacted clients within the next several days."