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CVE-2021-34473

Microsoft Exchange Server Remote Code Execution Vulnerability

Basic Information

CVE State
PUBLISHED
Reserved Date
June 09, 2021
Published Date
July 14, 2021
Last Updated
February 04, 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 Remote Code Execution Vulnerability
Tags
cisa malware ransomware nuclei_scanner microsoft metasploit_scanner

CVSS Scores

CVSS v3.1

9.1 - CRITICAL

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

SSVC Information

Exploitation
active
Automatable
Yes
Technical Impact
total

Exploit Status

Exploited in the Wild
Yes (2025-05-07 00:00:00 UTC) Source
Proof of Concept Available
Yes (added 2022-11-16 08:22:29 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-2021-34473 https://www.zerodayinitiative.com/advisories/ZDI-21-821/ 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

Scanner Integrations

Scanner URL Date Detected
Metasploit https://github.com/rapid7/metasploit-framework/blob/master/modules/exploits/windows/http/exchange_proxyshell_rce.rb 2025-04-29 11:01:37 UTC
Nuclei https://github.com/projectdiscovery/nuclei-templates/blob/main/http/cves/2021/CVE-2021-34473.yaml 2025-04-26 00:00:00 UTC

Potential Proof of Concepts

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

ipsBruno/CVE-2021-34473-NMAP-SCANNER

Type: github • Created: 2022-11-16 08:22:29 UTC • Stars: 2

A massive scanner for CVE-2021-34473 Microsoft Exchange Windows Vulnerability

je6k/CVE-2021-34473-Exchange-ProxyShell

Type: github • Created: 2021-11-22 07:47:09 UTC • Stars: 17

对Exchange Proxyshell 做了二次修改，精确的拆分、实现辅助性安全测试。

p2-98/CVE-2021-34473

Type: github • Created: 2021-08-16 11:27:13 UTC • Stars: 30

CVE-2021-34473 Microsoft Exchange Server Remote Code Execution Vulnerability

RaouzRouik/CVE-2021-34473-scanner

Type: github • Created: 2021-08-11 12:20:07 UTC • Stars: 6

Scanner for CVE-2021-34473, ProxyShell, A Microsoft Exchange On-premise Vulnerability

Timeline

  • CVE ID Reserved

  • CVE Published to Public

  • Exploit Used in Malware

  • Added to KEVIntel

  • Proof of Concept Exploit Available

  • Detected by Nuclei

  • Detected by Metasploit