A vulnerability has been identified in Yahoo! Chat and Messenger, which allows malicious people to cause a buffer overflow.

The problem is that the hostname parameter isn't verified properly in the Yahoo! Audio Conferencing ActiveX control. A hostname longer than 500 characters will cause the ActiveX control to crash when the "createandjoinconference" method is called.

If the hostname has been crafted in a malicious way, it could cause arbitrary code to be executed on the system.

The Yahoo! Audio Conferencing ActiveX control is marked as safe in Internet Explorer, thus the user will receive no warnings before the ActiveX control is launched.

Solution
Updated versions are available from Yahoo!:
Further details available to Secunia VIM customers

Provided and/or discovered by
Cesar Cerrudo

Deep Links
Links available to Secunia VIM customers