source: http://www.securityfocus.com/bid/17378/info
 
UltraVNC is susceptible to multiple error-logging remote buffer-overflow vulnerabilities. These issues are due to the application's failure to properly bounds-check user-supplied input before copying it to insufficiently sized memory buffers.
 
A successful attack may allow remote attackers to execute arbitrary code on a vulnerable computer to gain unauthorized access in the context of the application.

http://www.exploit-db.com/sploits/27569.zip