Improper Authentication in Microsoft Exchange Server - CVE-2021-33766
Published: July 13, 2021 / Updated: February 20, 2022
Vulnerability identifier: #VU54766
CSH Severity: Medium
CVSS v4.0: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N/E:A/U:Green
CVE-ID: CVE-2021-33766
CWE-ID: CWE-287
Exploitation vector: Remote access
Exploit availability:
The vulnerability is being exploited in the wild
Vendor: Microsoft
Affected software:
Microsoft Exchange Server
Microsoft Exchange Server
Detailed vulnerability description
The vulnerability allows a remote attacker to bypass authentication process.
The vulnerability exists due to an error in when processing authentication requests. A remote attacker can bypass authentication process and gain unauthorized access to the application.
The vulnerability was dubbed ProxyToken.
How to mitigate CVE-2021-33766
Install updates from vendor's website.