CVE-2021-31207 MEDIUM

CVE-2021-31207: Microsoft Exchange Server Security Feature Bypass Vulnerability

Vendor Microsoft
Product Microsoft Exchange Server 2013 Cumulative Update 23
KEV Status Known Exploited
Ransomware Used in campaigns
Published May 11, 2021
Last update October 21, 2025
View on NVD All CVEs

CVSS base score

6.6/10
Attack vector Network
Attack complexity High
Privileges required High
User interaction None
Confidentiality High
Integrity High

CVSS vector

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

What the vulnerability does

01Description

Microsoft Exchange Server Security Feature Bypass Vulnerability

CISA mandated remediation

02CISA Required Action

Apply updates per vendor instructions.

Key dates

03Disclosure timeline

May 11, 2021 CVE published
October 21, 2025 Record updated