CVE-2018-8340 Security feature bypass in Windows 10 Servers
Attackers can bypass multi-factor authentication in AD FS due to improper request handling, affecting Windows Server environments.
- 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-2018-8340?
CVE-2018-8340 is a medium-severity vulnerability in Microsoft Windows Server 2012, published on 15 Aug 2018. Any signed-in user can exploit it over the network, with no action from the victim.
Official description
A security feature bypass vulnerability exists when Active Directory Federation Services (AD FS) improperly handles multi-factor authentication requests, aka "AD FS Security Feature Bypass Vulnerability." This affects Windows Server 2016, Windows Server 2012 R2, Windows 10 Servers.
Which versions are affected by CVE-2018-8340?
It affects 2 products.
Products include Microsoft Windows Server 2012, Microsoft Windows Server 2016.
How do I fix CVE-2018-8340?
No fix has been published for CVE-2018-8340 yet. Limit exposure of the affected software until one is available.
Is CVE-2018-8340 being exploited?
There is no known exploitation of CVE-2018-8340 in the wild and no public exploit code.
Other vulnerabilities in Microsoft Windows Server 2012
- CVE-2025-59287 Microsoft Windows Server Update Service (WSUS) Deserialization of Untrusted Data
- CVE-2026-69595 Windows Services for NFS ONCRPC XDR Driver Remote Code Execution Vulnerability
- CVE-2026-78445 Windows Services for NFS ONCRPC XDR Driver Remote Code Execution Vulnerability
- CVE-2026-41089 Windows Netlogon Remote Code Execution Vulnerability
- CVE-2024-43639 Windows KDC Proxy Remote Code Execution Vulnerability
Sources
Also known as GHSA-4rgc-rj2m-g9gr.