CVE-2021-34523: Microsoft Exchange Server Privilege Escalation Vulnerability

Critical severity, CVSS 9.0. Actively exploited: in CISA KEV since 2021-11-03. EPSS: 100% chance of exploitation in the next 30 days.

Microsoft Exchange Server Elevation of Privilege Vulnerability

Affected products

• Microsoft Exchange Server: version 2013 only; version 2016 only; version 2019 only

Published 2021-07-14. Last modified 2026-08-10.