CVE-2025-64666
published 2025-12-09CVE-2025-64666: Improper input validation in Microsoft Exchange Server allows an authorized attacker to elevate privileges over a network.
PriorityP354high7.5CVSS 3.1
AVNACHPRLUINSUCHIHAH
EPSS
1.02%
59.5th percentile
Improper input validation in Microsoft Exchange Server allows an authorized attacker to elevate privileges over a network.
Affected
46 ranges· showing 25
| Vendor | Product | Version range | Fixed in |
|---|---|---|---|
| microsoft | exchange_server | — | — |
| microsoft | exchange_server | — | — |
| microsoft | exchange_server | — | — |
| microsoft | exchange_server | — | — |
| microsoft | exchange_server | — | — |
| microsoft | exchange_server | — | — |
| microsoft | exchange_server | — | — |
| microsoft | exchange_server | — | — |
| microsoft | exchange_server | — | — |
| microsoft | exchange_server | — | — |
| microsoft | exchange_server | — | — |
| microsoft | exchange_server | — | — |
| microsoft | exchange_server | — | — |
| microsoft | exchange_server | — | — |
| microsoft | exchange_server | — | — |
| microsoft | exchange_server | — | — |
| microsoft | exchange_server | — | — |
| microsoft | exchange_server | — | — |
| microsoft | exchange_server | — | — |
| microsoft | exchange_server | — | — |
| microsoft | exchange_server | — | — |
| microsoft | exchange_server | — | — |
| microsoft | exchange_server | — | — |
| microsoft | exchange_server | — | — |
| microsoft | exchange_server | — | — |
CVSS provenance
nvdv3.17.5HIGHCVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H
vendor_msrc7.5HIGH
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GHSA
GHSA-mr7p-99h9-v459: Improper input validation in Microsoft Exchange Server allows an authorized attacker to elevate privileges over a network
ghsa_unreviewed·2025-12-09
CVE-2025-64666 [HIGH] CWE-20 GHSA-mr7p-99h9-v459: Improper input validation in Microsoft Exchange Server allows an authorized attacker to elevate privileges over a network
Improper input validation in Microsoft Exchange Server allows an authorized attacker to elevate privileges over a network.
Microsoft
Microsoft Exchange Server Elevation of Privilege Vulnerability
vendor_msrc·2025-12-09·CVSS 7.5
CVE-2025-64666 [HIGH] CWE-20 Microsoft Exchange Server Elevation of Privilege Vulnerability
Microsoft Exchange Server Elevation of Privilege Vulnerability
Description: Improper input validation in Microsoft Exchange Server allows an authorized attacker to elevate privileges over a network.
FAQ: According to the CVSS metric, the attack complexity is high (AC:H). What does that mean for this vulnerability?
Successful exploitation of this vulnerability requires an attacker to take additional actions prior to exploitation to prepare the target environment.
FAQ: Why are update links missing for some Exchange products?
For Exchange Server 2016 and 2019, update links are not provided because these versions are out of support and security updates are only available through the Extended Security Update (ESU) program.
Customers enrolled in ESU can access the December 2025 and future upd
No detection rules found.
No public exploits indexed.
Bleepingcomputer
Microsoft December 2025 Patch Tuesday fixes 3 zero-days, 57 flaws
blogs_bleepingcomputer·2025-12-09·CVSS 7.8
[HIGH] Microsoft December 2025 Patch Tuesday fixes 3 zero-days, 57 flaws
## Microsoft December 2025 Patch Tuesday fixes 3 zero-days, 57 flaws
## Lawrence Abrams
28 Elevation of Privilege Vulnerabilities
19 Remote Code Execution Vulnerabilities
4 Information Disclosure Vulnerabilities
3 Denial of Service Vulnerabilities
2 Spoofing Vulnerabilities
When BleepingComputer reports on Patch Tuesday security updates, we only count those released by Microsoft today. Therefore, the number of flaws does not include Microsoft Edge (15 flaws) and Mariner vulnerabilities fixed earlier this month.
To learn more about the non-security updates released today, you can review our dedicated articles on the Windows 11 KB5072033 & KB5071417 cumulative updates .
If you're facing delays, blind spots, or prioritization issues with Patch Tuesday updates, our recent webinar with
Wiz
CVE-2025-64666 Impact, Exploitability, and Mitigation Steps | Wiz
blogs_wiz·CVSS 7.5
CVE-2025-64666 [HIGH] CVE-2025-64666 Impact, Exploitability, and Mitigation Steps | Wiz
## CVE-2025-64666 :
vulnerability analysis and mitigation
Improper input validation in Microsoft Exchange Server allows an authorized attacker to elevate privileges over a network.
Source : NVD
## 7.5
Score
Published December 9, 2025
Severity HIGH
CNA Score 7.5
Has Public Exploit No
Has CISA KEV Exploit No
CISA KEV Release Date N/A
CISA KEV Due Date N/A
Exploitation Probability Percentile (EPSS) 21.4
Exploitation Probability (EPSS) 0.1
Affected packages and libraries
cpe:2.3:a:microsoft:exchange_server:*:*:*:*:subscription:*:*:*
Sources
Windows Severity HIGH Has Fix Added at: Jan 03, 2026
Windows Severity HIGH Has Fix Added at: Jan 04, 2026
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2025-12-09
Published