CVE-2021-33766: 
vulnerability analysis and mitigation

Microsoft Exchange Server Information Disclosure Vulnerability (CVE-2021-33766) was discovered and reported on April 5, 2021, with public disclosure occurring on July 15, 2021. The vulnerability affects Microsoft Exchange Server installations, specifically within the Exchange Control Panel (ECP) web application (ZDI Advisory).

The vulnerability exists within the authentication mechanism of requests to web services within the ECP web application. The flaw allows remote attackers to bypass authentication through crafted requests. The vulnerability has been assigned a CVSS score of 6.5 (AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:L/A:N), indicating a moderate to high severity (ZDI Advisory).

When exploited, this vulnerability enables remote attackers to disclose sensitive information from affected Microsoft Exchange Server installations. The attack does not require authentication to execute, making it particularly concerning for exposed systems (ZDI Advisory).

The vulnerability can be exploited remotely without requiring authentication. An attacker can leverage this vulnerability by issuing specially crafted requests to the server, potentially leading to unauthorized information disclosure (ZDI Advisory).

Microsoft has released a security update to address this vulnerability. Organizations running affected versions of Microsoft Exchange Server should apply the update KB5001779 as soon as possible (Rapid7).