Input validation error in Microsoft Exchange Server - CVE-2025-64666
Published: December 9, 2025
Vulnerability identifier: #VU119438
CSH Severity: Medium
CVSS v4: 7.7 [CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N]
CVE-ID: CVE-2025-64666
CWE-ID: CWE-20
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a remote user to escalate privileges within the application.
The vulnerability exists due to insufficient validation of user-supplied input. A remote user can send a specially crafted request to the mail server and gain administrator privileges.
Affected software
Microsoft Exchange Server
How to mitigate CVE-2025-64666
Install updates from vendor's website.
Microsoft Exchange Server - addressed in versions SE RTM Dec25SU 15.02.2562.035, 2016 CU23 Dec25SU 15.01.2507.063, 2019 CU14 Dec25SU 15.02.1544.037, 2019 CU15 Dec25SU 15.02.1748.042