CVE-2021-34523

CISA KEV RANSOMWARE

ACT NOW Priority: 0.00 BB Relevance: 0/100

Published: N/A Modified: N/A First seen: 2026-10-29 Status: pending_score

Description

Microsoft Exchange Server contains an unspecified vulnerability that allows for privilege escalation.

CISA Known Exploited Vulnerability

Vendor / Product Microsoft — Exchange Server

Date Added 2021-11-03

Remediation Due 2021-11-17

Ransomware Use CONFIRMED

https://nvd.nist.gov/vuln/detail/CVE-2021-34523

Affected Software (5)

Vendor	Product	Version
microsoft	exchange_server	2013
microsoft	exchange_server	2016
microsoft	exchange_server	2016
microsoft	exchange_server	2019
microsoft	exchange_server	2019

References & Advisories (5)

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

US Government Resource

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

Third Party Advisory VDB Entry

https://msrc.microsoft.com/update-guide/vulnerability/CVE-2021-34523

Patch Vendor Advisory

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

Patch Vendor Advisory

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

Exploit Third Party Advisory VDB Entry

Bug Bounty Relevance

0 / 100

✓ Known exploited (KEV)

CVSS Score

Unscored

EPSS — Exploitation Probability

No EPSS data available

Intelligence Sources

kev ref →

External Links

NVD (NIST) CVE Details FIRST EPSS API OSV.dev