source: http://www.securityfocus.com/bid/1088/info

Unchecked buffer code exists in the 'location' field of Real Networks RealPlayer versions 6.0 and 7.0. Requesting a URL containing a string consisting of 300 or more characters would cause the application to crash and would require a restart in order to regain normal functionality. Arbitrary code can potentially be executed through this vulnerability.

This vulnerability may be exploited remotely if such a URL were embedded in a HTML file with the command 'autostart' set as 'true'. Both RealPlayer and the accompanying browser would crash in this case and require to be restarted to regain functionality.

So far only the Windows versions of the Real Player have been proven to be vulnerable in this manner. 

http://<string containing over 300 characters>