# CVE-2026-85324: Microsoft Active Directory Federation Services memory allocation denial of service

Source: https://junglewise.ai/threats/cve-2026-85324-memory-allocation-with-excessive-size-value-in-active-directory  
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-2026-85324 · Severity: high · CVSS 7.5 · Published 2026-10-13

Active Directory Federation Services (AD FS) is Microsoft's authentication and identity management system used by enterprises to secure access to corporate applications and resources. An attacker can remotely crash AD FS by sending specially crafted network requests that trigger excessive memory allocation, disrupting authentication services for all users until the service is restarted.

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 2012](https://junglewise.ai/threats/technologies/windows-server-2012), [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-2026-85324 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-85324 being exploited in the wild.

**How severe is CVE-2026-85324?** High severity, with a CVSS score of 7.5, published 13 October 2026.

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

**Is there a fix for CVE-2026-85324?** 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-2026-85324 attacked?** It is attacked over the network, in a hosted service.

**Am I affected by CVE-2026-85324?** 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

A memory allocation vulnerability in AD FS allows an unauthenticated attacker to trigger a denial of service condition by supplying an excessive size value in a network request, causing the service to exhaust memory and crash. The vulnerability is reachable over the network without requiring prior authentication or user interaction. An exploit results in service unavailability but does not allow code execution or data access.

## Affected products

- Microsoft Active Directory Federation Services

## Timeline

- 2026-10-13: disclosed

## References

- [https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-85324](https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-85324)

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