# CVE-2026-83674: Microsoft Active Directory Federation Services weak authentication

Source: https://junglewise.ai/threats/cve-2026-83674-weak-authentication-in-active-directory-federation-services-ad-fs  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-10-13. Updated: 2026-10-29  
License: CC BY 4.0 with a link back

CVE-2026-83674 · Severity: high · CVSS 8.1 · Published 2026-10-13

Active Directory Federation Services (AD FS) is Microsoft's authentication system that manages identity access for enterprise networks and cloud services. Weak authentication mechanisms in AD FS allow attackers to spoof identities and gain unauthorized access to protected resources without valid credentials, posing a risk of account takeover and data breaches across organizations using federated identity management.

Technologies: [Microsoft Active Directory Federation Services](https://junglewise.ai/threats/technologies/active-directory-federation-services), [Microsoft Windows 10 1607](https://junglewise.ai/threats/technologies/windows-10-1607), [Microsoft Windows 10 1809](https://junglewise.ai/threats/technologies/windows-10-1809), [Microsoft Windows Server 2016](https://junglewise.ai/threats/technologies/windows-server-2016), [Microsoft Windows Server 2019](https://junglewise.ai/threats/technologies/windows-server-2019), [Microsoft Windows Server 2022](https://junglewise.ai/threats/technologies/windows-server-2022), [Microsoft Windows Server 2025](https://junglewise.ai/threats/technologies/windows-server-2025). Vendors: [Microsoft](https://junglewise.ai/threats/vendors/microsoft).

## Quick answers

**Is CVE-2026-83674 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-83674 being exploited in the wild.

**How severe is CVE-2026-83674?** High severity, with a CVSS score of 8.1, published 13 October 2026.

**Which products and versions are affected?** Microsoft Active Directory Federation Services.

**Is there a fix for CVE-2026-83674?** No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.

**How is CVE-2026-83674 attacked?** It is attacked over the network, in a hosted service.

**Am I affected by CVE-2026-83674?** Check whether you run Microsoft Active Directory Federation Services, Microsoft Windows 10 1607, Microsoft Windows 10 1809 or one of the others listed. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## Technical details

The vulnerability stems from weak authentication validation in AD FS, enabling spoofing attacks over the network without requiring prior authentication or special privileges. An unauthenticated remote attacker can exploit this to impersonate legitimate users or services. The weakness allows attackers to bypass identity verification mechanisms central to federated authentication.

## Affected products

- Microsoft Active Directory Federation Services

## Timeline

- 2026-10-13: disclosed

## References

- [https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-83674](https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-83674)

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