Application Logic Error in DT Centrepiece

Vulnerability ID: HTB22522
Reference: http://www.htbridge.ch/advisory/application_logic_error_in_dt_centrepiece.html
Product: DT Centrepiece
Vendor: DT Services ( http://www.dt.net.nz/ )
Vulnerable Version: 4.5 and Probably Prior Versions
Vendor Notification: 22 July 2010
Vulnerability Type: Application Logic Error
Status: Not Fixed, Vendor Alerted, Awaiting Vendor Response
Risk level: Low
Credit: High-Tech Bridge SA - Ethical Hacking & Penetration Testing (http://www.htbridge.ch/)

Vulnerability Details:
The user can activate an arbitrary account.

The system account is activated, has a predictable URL. This allows the user to activate any account without receiving the activation email.

The following PoC is available:

http://host/activate.asp?p=USERNAME