CVE-2025-64666 HIGH

CVE-2025-64666: Microsoft Exchange Server Elevation of Privilege Vulnerability

Vendor Microsoft
Product Microsoft Exchange Server 2016 Cumulative Update 23
Weakness CWE-20 · Input validation
Published December 9, 2025
Last update April 16, 2026
View on NVD All CVEs

CVSS base score

7.5/10
Attack vector Network
Attack complexity High
Privileges required Low
User interaction None
Confidentiality High
Integrity High

CVSS vector

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

What the vulnerability does

01Description

Improper input validation in Microsoft Exchange Server allows an authorized attacker to elevate privileges over a network.

Key dates

02Disclosure timeline

December 9, 2025 CVE published
April 16, 2026 Record updated