CVE-2021-34473
Microsoft Exchange Server Remote Code Execution Vulnerability
KEV RANSOMWARECRITICAL 9.8EPSS 100.0%
Microsoft Exchange Server Remote Code Execution Vulnerability
- Affected
- Microsoft · Microsoft Exchange Server 2013 Cumulative Update 23 · Microsoft Exchange Server 2016 Cumulative Update 19 · Microsoft Exchange Server 2016 Cumulative Update 20 · Microsoft Exchange Server 2019 Cumulative Update 8 · Microsoft Exchange Server 2019 Cumulative Update 9
- CVSS v3.1 NVD
- 9.8 CRITICAL
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H - CVSS v3.1 MICROSOFT
- 9.1 CRITICAL
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N - CVSS v2.0 NVD
- 10.0 HIGH
AV: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-ProxyShell16★ · 2021-11-23
- kh4sh3i/ProxyShell43★ · 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)
Metasploit modules (1)
Security advisories
- https://msrc.microsoft.com/update-guide/vulnerability/CVE-2021-34473
- https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-34473
- https://www.zerodayinitiative.com/advisories/ZDI-21-821