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CVE-2021-34523

Microsoft Exchange Server Elevation of Privilege Vulnerability

Basic Information

CVE State
PUBLISHED
Reserved Date
June 09, 2021
Published Date
July 14, 2021
Last Updated
October 21, 2025
Vendor
Microsoft
Product
Microsoft Exchange Server 2013 Cumulative Update 23, Microsoft Exchange Server 2019 Cumulative Update 9, Microsoft Exchange Server 2016 Cumulative Update 20, Microsoft Exchange Server 2016 Cumulative Update 19, Microsoft Exchange Server 2019 Cumulative Update 8
Description
Microsoft Exchange Server Elevation of Privilege Vulnerability
Tags
cisa malware ransomware metasploit microsoft

CVSS Scores

CVSS v3.1

9.0 - CRITICAL

Vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:N/E:U/RL:O/RC:C

SSVC Information

Exploitation
active
Technical Impact
total

Exploit Status

Exploited in the Wild
Yes (2021-11-03 00:00:00 UTC) Source
Used in Malware
Yes (added 2021-11-03 00:00:00 UTC) Source

References

https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-34523 https://www.zerodayinitiative.com/advisories/ZDI-21-822/ http://packetstormsecurity.com/files/163895/Microsoft-Exchange-ProxyShell-Remote-Code-Execution.html

Known Exploited Vulnerability Information

Source Added Date
CISA 2021-11-03 00:00:00 UTC
CISA 2021-11-03 00:00:00 UTC

Scanner Integrations

Scanner URL Date Detected
Metasploit https://github.com/rapid7/metasploit-framework/blob/master/modules/exploits/windows/http/exchange_proxyshell_rce.rb 2025-04-28 15:02:52 UTC

Potential Proof of Concepts

Warning: These PoCs have not been tested and could contain malware. Use at your own risk.

SUPRAAA-1337/CVE-2021-34523

Type: github • Created: 2023-09-02 12:26:18 UTC • Stars: 2

test-yaml

Timeline

  • CVE ID Reserved

  • CVE Published to Public

  • Exploit Used in Malware

  • Added to KEVIntel

  • Added to KEVIntel

  • Detected by Metasploit