Absolute path traversal vulnerability in a certain ActiveX control in the CYFT object in ft60.dll in Yahoo! Messenger 8.1.0.421 allows remote attackers to force a download, and create or overwrite arbitrary files via a full pathname in the second argument to the GetFile method.
Yahoo! Messenger 5.0 allows remote attackers to spoof other users by modifying the username and using the spoofed username for social engineering or denial of service (flooding) attacks.