CVE-2021-34473

9.1 CRITICAL CISA KEV - Actively Exploited

Published: July 14, 2021 Modified: October 29, 2025

View on NVD

Description

Microsoft Exchange Server Remote Code Execution Vulnerability

AI Explanation

Get an AI-powered plain-language explanation of this vulnerability and remediation steps.

CVSS v3.x Details

0.0 Low Medium High Critical 10.0

Vector String

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

References to Advisories, Solutions, and Tools

Patch Vendor Advisory Exploit Third Party Advisory

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

Source: secure@microsoft.com

Exploit Third Party Advisory VDB Entry

https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-34473

Source: secure@microsoft.com

Patch Vendor Advisory

https://www.zerodayinitiative.com/advisories/ZDI-21-821/

Source: secure@microsoft.com

Third Party Advisory VDB Entry

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

Source: af854a3a-2127-422b-91ae-364da2661108

Exploit Third Party Advisory VDB Entry

https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-34473

Source: af854a3a-2127-422b-91ae-364da2661108

Patch Vendor Advisory

https://www.zerodayinitiative.com/advisories/ZDI-21-821/

Source: af854a3a-2127-422b-91ae-364da2661108

Third Party Advisory VDB Entry

https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-34473

Source: 134c704f-9b21-4f2e-91b3-4a467353bcc0

US Government Resource

7 reference(s) from NVD

Quick Stats

CVSS v3 Score

9.1 / 10.0

EPSS (Exploit Probability)

94.2%

100th percentile

Exploitation Status

Actively Exploited

Remediation due: 2021-11-17

Weaknesses (CWE)

CWE-918 CWE-918

Affected Vendors

microsoft

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