CVE-2025-64666 Microsoft Exchange Server Elevation of Privilege Vulnerability
An authorized attacker can elevate privileges on Microsoft Exchange Server due to improper input validation, requiring immediate patching.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2025-64666?
CVE-2025-64666 is a high-severity vulnerability in Microsoft Exchange Server, published on 9 Dec 2025. Any signed-in user can exploit it over the network, with no action from the victim.
Official description
Improper input validation in Microsoft Exchange Server allows an authorized attacker to elevate privileges over a network.
Weakness: CWE-20
Which versions are affected by CVE-2025-64666?
It affects 2 products.
Products include Microsoft Exchange Server, Microsoft Exchange Server Subscription Edition.
How do I fix CVE-2025-64666?
No fix has been published for CVE-2025-64666 yet. Limit exposure of the affected software until one is available.
Is CVE-2025-64666 being exploited?
There is no known exploitation of CVE-2025-64666 in the wild and no public exploit code.
Other vulnerabilities in Microsoft Exchange Server
- CVE-2024-21410 Microsoft Exchange Server Privilege Escalation
- CVE-2021-34473 Microsoft Exchange Server Remote Code Execution
- CVE-2021-26855 Microsoft Exchange Server Remote Code Execution
- CVE-2021-34523 Microsoft Exchange Server Privilege Escalation
- CVE-2023-21529 Microsoft Exchange Server Deserialization of Untrusted Data
Sources
Also known as GHSA-mr7p-99h9-v459.