Advisory Details

July 15th, 2021

Microsoft Exchange Server ECP Authentication Bypass Information Disclosure Vulnerability

ZDI-21-798
ZDI-CAN-13477

CVE ID CVE-2021-33766
CVSS SCORE 6.5, (AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:L/A:N)
AFFECTED VENDORS Microsoft
AFFECTED PRODUCTS Exchange
VULNERABILITY DETAILS

This vulnerability allows remote attackers to disclose sensitive information on affected installations of Microsoft Exchange Server. Authentication is not required to exploit this vulnerability.

The specific flaw exists within the authentication of requests to web services within the ecp web application. By issuing a crafted request, an attacker can bypass authentication. An attacker can leverage this vulnerability to disclose information from the server.

ADDITIONAL DETAILS Microsoft has issued an update to correct this vulnerability. More details can be found at:
https://msrc.microsoft.com/update-guide/vulnerability/CVE-2021-33766
DISCLOSURE TIMELINE
  • 2021-04-05 - Vulnerability reported to vendor
  • 2021-07-15 - Coordinated public release of advisory
CREDIT LE XUAN TUYEN - VNPT ISC
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