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CVE-2021-34523

Known Exploited (CISA KEV)CRITICAL

9.0

CVSS Severity Score

EPSS Score38.0840%

EPSS Percentile96.42th

PublishedJul 14, 2021

Last ModifiedOct 30, 2025

Vulnerability Description

Microsoft Exchange Server Elevation of Privilege Vulnerability

Affected Platforms (CPE)

📦

Microsoft

Exchange Server

= 2013

📦

Microsoft

Exchange Server

= 2016

📦

Microsoft

Exchange Server

= 2016

📦

Microsoft

Exchange Server

= 2019

📦

Microsoft

Exchange Server

= 2019

References & Advisories

🔗 http://packetstormsecurity.com/files/163895/Microsoft-Exchange-ProxyShell-Remote-Code-Execution.html

🔗 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

🔗 https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-34523

🔗 https://www.zerodayinitiative.com/advisories/ZDI-21-822/

🔗 https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-34523

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