ActiveX element allow to upload and execute any code.
CVE:
CVE-2007-1402 (The Rediff Toolbar 2.0 ActiveX control in redifftoolbar.dll allows remote attackers to cause a denial of service via unspecified manipulations, possibly involving improper initialization or blank arguments.)
CVE-2006-6838 (Rediff Bol Downloader ActiveX (OCX) control allows remote attackers to execute arbitrary files, and obtain sensitive information (usernames and pathnames), via a URL in the url vbscript parameter.)