# CVE-2026-83646: Microsoft Active Directory Federation Services open redirect

Source: https://junglewise.ai/threats/cve-2026-83646-url-redirection-to-untrusted-site-open-redirect-in-active  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-10-13. Updated: 2026-10-16  
License: CC BY 4.0 with a link back

CVE-2026-83646 · Severity: medium · CVSS 4.8 · Published 2026-10-13

Active Directory Federation Services (AD FS) is Microsoft's identity federation server that handles single sign-on for enterprise networks. An authorized attacker can exploit an open redirect vulnerability to craft malicious links that appear to come from AD FS but redirect users to untrusted sites, enabling credential theft or spoofing attacks. The attacker must already have authorization to the system to exploit this issue.

Technologies: [Microsoft Active Directory Federation Services](https://junglewise.ai/threats/technologies/active-directory-federation-services). Vendors: [Microsoft](https://junglewise.ai/threats/vendors/microsoft).

## Quick answers

**Is CVE-2026-83646 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-83646 being exploited in the wild.

**How severe is CVE-2026-83646?** Medium severity, with a CVSS score of 4.8, published 13 October 2026.

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

**Is there a fix for CVE-2026-83646?** 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-2026-83646 attacked?** It is attacked over the network, in a hosted service.

**Am I affected by CVE-2026-83646?** Check whether you run Microsoft Active Directory Federation Services. 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

This is an open redirect vulnerability in AD FS that allows an authorized attacker to craft URLs that redirect users to untrusted external sites. The vulnerability requires existing authorization to the AD FS system. An attacker could use this to perform credential harvesting or social engineering through trusted-looking redirect chains.

## Affected products

- Microsoft Active Directory Federation Services

## Timeline

- 2026-10-13: disclosed

## References

- [https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-83646](https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-83646)

## Related threats

- [Microsoft Active Directory Federation Services information disclosure](https://junglewise.ai/threats/cve-2026-97788-observable-discrepancy-in-active-directory-federation-services-ad)
- [Microsoft Active Directory Federation Services cryptographic signature verification bypass](https://junglewise.ai/threats/cve-2026-96252-improper-verification-of-cryptographic-signature-in-active)
- [Microsoft Active Directory Federation Services memory allocation denial of service](https://junglewise.ai/threats/cve-2026-85324-memory-allocation-with-excessive-size-value-in-active-directory)
- [Microsoft Active Directory Federation Services resource exhaustion denial of service](https://junglewise.ai/threats/cve-2026-85319-allocation-of-resources-without-limits-or-throttling-in-active)
- [Microsoft Active Directory Federation Services weak authentication](https://junglewise.ai/threats/cve-2026-83674-weak-authentication-in-active-directory-federation-services-ad-fs)