EUVD-2026-43855
GHSA-xrh5-vqqv-gc4m
Vulnerability Assessment
| Weakness |
CWE
ASVS 5.0
V15 - Secure Coding and Architecture Stack buffer bounds checking
MITRE ATT&CK
1 technique across 1 tactic: Execution The technique list with ATT&CK links and the kill-chain view is part of the Basic plan and up. |
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Alert meAnalysisAIv1 – Jul 14, 2026
Denial of service in Microsoft Active Directory Federation Services (AD FS) lets a remote, unauthenticated attacker crash the service by triggering a stack-based buffer overflow (CWE-121) over the network. Because AD FS commonly fronts single sign-on for Microsoft 365, SaaS, and internal web applications, a successful crash can knock out federated authentication for an entire organization. No public exploit identified at time of analysis, and the flaw is availability-only — confidentiality and integrity are not impacted per the CVSS vector.
Affected VersionsENISA
Affected Packages
Source: OSV (Open Source Vulnerabilities)
Affects your stack
Affects 13 packages in euvd
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- Exploit and PoC references, threat intelligence from 22 sources
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Severity by source
AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Primary rating from Vendor (microsoft) · only source for this CVE.
CVSS VectorVendor: microsoft
DescriptionCVE.org
Stack-based buffer overflow in Active Directory Federation Services allows an unauthorized attacker to deny service over a network.
Executive ViewAI
Microsoft Active Directory Federation Services (AD FS) faces a remote denial-of-service vulnerability that allows unauthenticated attackers to crash the service, directly disrupting organization-wide single sign-on for Microsoft 365, SaaS applications, and internal web services. No public exploit identified at time of analysis, but a vendor patch is available. Immediate patching is critical to prevent organization-wide authentication outages.
Within 24 hours, identify all AD FS servers in your environment and obtain the vendor patch matching your deployed version; develop a patching timeline aligned with your AD FS redundancy and maintenance windows. Within 7 days, deploy the patch to all AD FS infrastructure and verify that federated authentication functions correctly for Microsoft 365 and all connected SaaS applications. Within 30 days, implement continuous monitoring for AD FS service health and complete post-deployment testing of federated authentication workflows.
Apply vendor patch. Interim mitigation: restrict network access to AD FS endpoints to trusted networks only; ensure AD FS deployment includes redundancy to enable service failover during patching.
Threat Intelligence Overview
NVD
CVE.org
EPSS
Vulnrichment
VulDB
How this decision was reached
The engine reads each signal below and applies a fixed list of rules from top to bottom. The first rule that matches sets the recommended action – like a statement, every line is shown.
What every action level means
SSVC AssessmentENISA
Priority Score
Attack Technique
A buffer overflow occurs when a program writes more data to a memory buffer than it was allocated to hold, causing the excess data to spill into adjacent memory regions.
A stack-based buffer overflow occurs when a program writes more data to a buffer located on the stack than it was allocated to hold.
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