CVE-2021-34523
Microsoft Exchange Server Elevation of Privilege Vulnerability
KEV RANSOMWARECRITICAL 9.8EPSS 100.0%
Microsoft Exchange Server Elevation of Privilege 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
- 9.0 CRITICAL
CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:N - CVSS v2.0 NVD
- 7.5 HIGH
AV:N/AC:L/Au:N/C:P/I:P/A:P - EPSS
- 99.99% chance of exploitation in the next 30 days, 100th percentile
- CISA KEV
- added 2021-11-03, used in ransomware campaigns
- Published
- 2021-07-14
- Updated
- 2026-08-10
Proof-of-concept exploits (6)
- http://packetstormsecurity.com/files/163895/Microsoft-Exchange-ProxyShell-Remote-Code-Exe…
- SUPRAAA-1337/CVE-2021-345232★ · 2023-09-02
- aravazhimdr/ProxyShell-POC-Mod6★ · 2021-08-18
- horizon3ai/proxyshell121★ · 2023-08-25
- mithridates1313/ProxyShell_POC16★ · 2021-10-06
- swaptt/swapt-it0★ · 2022-04-10
Metasploit modules (1)
Security advisories
- https://msrc.microsoft.com/update-guide/vulnerability/CVE-2021-34523
- https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-34523
- https://www.zerodayinitiative.com/advisories/ZDI-21-822