Application Logic Error in DT Centrepiece

Vulnerability ID: HTB22523
Reference: http://www.htbridge.ch/advisory/application_logic_error_in_dt_centrepiece_1.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 in the Authentication Mechanism
Status: Not Fixed, Vendor Alerted, Awaiting Vendor Response
Risk level: High
Credit: High-Tech Bridge SA - Ethical Hacking & Penetration Testing (http://www.htbridge.ch/)

Vulnerability Details:
The user can get access to the account of an arbitrary user.
When a user logs in, the remember password system puts predictable data in the cookie.

An attacker can use browser to exploit this vulnerability. The following PoC is available:

Just put this values in cookie:

MM_Remember_Username=USERNAME