CVE-2026-83674 Active Directory Federation Services (AD FS) Spoofing Vulnerability
Weak authentication in AD FS allows attackers to perform spoofing over the network, requiring patches for Windows Server and Windows 10.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2026-83674?
CVE-2026-83674 is a high-severity authentication bypass vulnerability in Microsoft Windows 10 1607, published on 13 Oct 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
Weak authentication in Active Directory Federation Services (AD FS) allows an unauthorized attacker to perform spoofing over a network.
Weakness: CWE-1390
Which versions are affected by CVE-2026-83674?
It affects 6 products.
Products include Microsoft Windows 10 1607, Microsoft Windows 10 1809, Microsoft Windows Server 2016, Microsoft Windows Server 2019, Microsoft Windows Server 2022, Microsoft Windows Server 2025.
How do I fix CVE-2026-83674?
No fix has been published for CVE-2026-83674 yet. Limit exposure of the affected software until one is available.
Upgrade, and rotate credentials and sessions that may have been exposed. More about Authentication bypass.
Is CVE-2026-83674 being exploited?
There is no known exploitation of CVE-2026-83674 in the wild and no public exploit code.
Other vulnerabilities in Microsoft Windows 10 1607
- CVE-2026-33824 Microsoft Internet Key Exchange (IKE) Service Extensions Double Free
- CVE-2026-21510 Microsoft Windows Shell Protection Mechanism Failure
- CVE-2026-21513 Microsoft MSHTML Framework Protection Mechanism Failure
- CVE-2023-32049 Microsoft Windows Defender SmartScreen Security Feature Bypass
- CVE-2023-29360 Microsoft Streaming Service Untrusted Pointer Dereference
Sources
Also known as GHSA-f3fh-9v4g-62gx.