CVE intelligenceCISA KEVRansomware use

CVE-2021-27065

Microsoft Exchange Server Remote Code Execution Vulnerability

Published Mar 3, 2021Sources checked Sep 12, 2026

7.8HIGHCVSS out of 10

What this means

Actively exploited

CISA lists CVE-2021-27065 in its Known Exploited Vulnerabilities catalog, which means exploitation has been observed. The entry applies to Microsoft Exchange Server.

Apply updates per vendor instructions.

CISA KEVListedObserved exploitation

EPSS99.9%Estimated 30-day exploitation probability

Ransomware useReported by CISACISA KEV ransomware field

Threat actors1Source-linked actor relationships

Overview

What is CVE-2021-27065?

Microsoft Exchange Server Remote Code Execution Vulnerability