In the current download, the security weakness Heartbleed is corrected. Users should change their passwords to exchanges.
Centrabit´s CTO Ighor July has corrected the weakness disovered yesterday morning and urges users of the Windows version to download the update at the dowload page.
For information about the weakness itself, see heartbleed.com. We urge all users to reset exchange passwords now. The main password for Qt Bitcoin Trader is and was safe.