Improper input validation in Microsoft Exchange Server 2016 Cumulative Update 23
CVE-2025-64666
Improper input validation in Microsoft Exchange Server allows an authorized attacker to elevate privileges over a network.
Vulnerability class: Drupalgeddon 2 (CVE-2018-7600)
EPSS: 0.000 (15.5th percentile) — read the EPSS interpretation.
CVSS v3 metric
CVSS v3 base score 7.5 (High). 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.
Affected products
- Microsoft Exchange Server 2016 Cumulative Update 23 — versions 15.01.0.0
- Microsoft Exchange Server 2019 Cumulative Update 14 — versions 15.02.0.0
- Microsoft Exchange Server 2019 Cumulative Update 15 — versions 15.02.0.0
- Microsoft Exchange Server Subscription Edition Rtm — versions 15.02.0.0
Weakness classification (CWE)
References
- Microsoft Exchange Server Elevation of Privilege Vulnerability (vendor-advisory, patch)
Frequently asked questions
- What is CVE-2025-64666?
- CVE-2025-64666 is a high-severity vulnerability in Microsoft Exchange Server 2016 Cumulative Update 23, classified under Improper Input Validation. CVSS score: 7.5/10. Published 2025-12-09.
- How severe is CVE-2025-64666?
- High severity. CVSS v3 base score is 7.5 out of 10.