CVE-2021-34523 CRITICAL

CVE-2021-34523: Microsoft Exchange Server Elevation of Privilege Vulnerability

Vendor Microsoft
Product Microsoft Exchange Server 2013 Cumulative Update 23
KEV Status Known Exploited
Ransomware Used in campaigns
Published July 14, 2021
Last update October 21, 2025
View on NVD All CVEs

CVSS base score

9.0/10
Attack vector Local
Attack complexity Low
Privileges required None
User interaction None
Confidentiality High
Integrity High

CVSS vector

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

What the vulnerability does

01Description

Microsoft Exchange Server Elevation of Privilege Vulnerability

CISA mandated remediation

02CISA Required Action

Apply updates per vendor instructions.

Key dates

03Disclosure timeline

July 14, 2021 CVE published
October 21, 2025 Record updated