source: https://www.securityfocus.com/bid/49361/info

ClickCMS is prone to a denial-of-service vulnerability and a CAPTCHA-bypass vulnerability.

Attackers can leverage these issues to cause the affected server to stop responding or to bypass certain security mechanisms. 

http://www.example.com/captcha/CaptchaSecurityImages.php?width=150&height=100&characters=2
http://www.example.com/captcha/CaptchaSecurityImages.php?width=1000&height=9000