My previous post was based on an incomplete test scenario.
what i can say by now is – i can reproduce the bug on Windows XP with 1.1 and even 1.1 SP1.
i cannot reproduce the bug on Windows 2003 with and without the service pack.
you can try yourself if you are vulnerable. fritz hacked up a quick proof of concept web app. download it and try if the following url gives you “you shouldn’t be able to see this without authenticating”. FormSec.zip (12,84 KB)