Inge Henriksen Security Advisory - Full Disclosure Proof of Concept at http://ingehenriksen.blogspot.com/ 
Advisory Name: IE7 website security certificate discrediting exploit
Tested and Confirmed Vulnerable: Microsoft(R) Internet Explorer(R) 7 

Severity: Low
Type: Spoof
From where: Remote
Discovered by: Inge Henriksen (http://ingehenriksen.blogspot.com/)
Vendor Status: Notified
Overview:

It is possible to create a link in Microsoft(R) Internet Explorer(R) 7 that discredits a websites security certificate. The bad design is in the ieframe.dll's embedded invalidecert.htm.

Full Disclosure Proof of Concept at http://ingehenriksen.blogspot.com/