CVE-2021-34473

Microsoft Exchange Server Remote Code Execution Vulnerability

CVSS v3.1

9.8 CRITICALCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

CVSS v3.1

9.1 CRITICALCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N

CVSS v2.0

10.0 HIGHAV:N/AC:L/Au:N/C:C/I:C/A:C

EPSS

100.00% chance of exploitation in the next 30 days, 100th percentile

CISA KEV

added 2021-11-03, used in ransomware campaigns

Nuclei

critical · CWE-918

Published

2021-07-14

Updated

2026-08-10

Proof-of-concept exploits (10)

• http://packetstormsecurity.com/files/163895/Microsoft-Exchange-ProxyShell-Remote-Code-Exe…
• aravazhimdr/ProxyShell-POC-Mod6★ · 2021-08-18
• horizon3ai/proxyshell121★ · 2023-08-25
• je6k/CVE-2021-34473-Exchange-ProxyShell17★ · 2021-11-23
• kh4sh3i/ProxyShell42★ · 2022-06-30
• learningsurface/ProxyShell-CVE-2021-34473.py0★ · 2022-01-17
• mithridates1313/ProxyShell_POC16★ · 2021-10-06
• p2-98/CVE-2021-3447330★ · 2021-08-16
• phamphuqui1998/CVE-2021-3447330★ · 2021-08-16
• swaptt/swapt-it0★ · 2022-04-10

Nuclei templates (1)

• projectdiscovery/nuclei-templates/blob/main/http/cves/2021/CVE-2021-34473.yaml

Metasploit modules (1)

• rapid7/metasploit-framework/blob/master/modules/exploits/windows/http/exchange_proxyshell…

References

• CVE Record
• NVD entry

Related

• CVE-2021-31207
• CVE-2021-34523
• CVE-2020-18157
• CVE-2018-13379
• CVE-2019-3396
• CVE-2021-22214