Microsoft Outlook Express has been reported prone to a URI obfuscation vulnerability.
This issue is reported to affect version 6.0 of the affected software, other versions might also be affected.
An attacker could reportedly get a user to visit an attacker controlled site without the usual address bar feature in a web browser. This could potentially make it easier for an attacker to fool a user into trusting the site contents.
<BASE href=http://www.example1.com target=_top>