Microsoft CVE-2017-8621: Microsoft Exchange Open Redirect Vulnerability

An open redirect vulnerability exists in Microsoft Exchange that could lead to spoofing. To exploit the vulnerability, an attacker could send a link that has a specially crafted URL, and convince the user to click the link. When an authenticated Exchange user clicks the link, the authenticated user's browser session could be redirected to a malicious site that is designed to impersonate a legitimate website. By doing so, the attacker could trick the user and potentially acquire sensitive information, such as the user's credentials. The update addresses the vulnerability by correcting how Exchange handles open redirect requests.