EUVD-2026-22481
GHSA-6qx2-q8q2-jv3c
Severity by source
AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:N
Primary rating from NVD.
CVSS VectorNVD
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:N
Lifecycle Timeline
6DescriptionCVE.org
Improper input validation in Windows Hello allows an unauthorized attacker to bypass a security feature over a network.
AnalysisAI
Windows Hello authentication bypass on Server 2016-2025 allows unauthenticated remote attackers to circumvent biometric/PIN security mechanisms over a network despite high attack complexity. CVSS 8.7 (Critical) with scope change indicates potential lateral movement from compromised Hello authentication into broader Windows security context. Vendor-released patches available for all affected versions (builds 10.0.14393.9060, 10.0.17763.8644, 10.0.20348.5020, 10.0.25398.2274, 10.0.26100.32690). No confirmed active exploitation (CISA KEV) or public exploit code identified at time of analysis, though VulDB tracking suggests security community awareness.
Technical ContextAI
Windows Hello is Microsoft's biometric authentication framework integrated into Windows Server environments, providing passwordless authentication via face recognition, fingerprint, or PIN. CWE-20 (Improper Input Validation) indicates the vulnerability stems from insufficient sanitization of network-transmitted authentication data, likely during the Hello credential validation handshake or certificate-based authentication exchange. The CVSS scope change (S:C) suggests the flaw exists in a privilege boundary between Windows Hello authentication components and the underlying operating system security context, enabling attackers to escape the intended security perimeter. Affects all modern Windows Server versions from 2016 through 2025, including Server Core installations which typically run domain controllers and critical infrastructure-environments where biometric/PIN authentication mechanisms may be deployed for administrative access or hybrid identity scenarios integrating Azure AD with Windows Hello for Business.
RemediationAI
Apply Microsoft security updates immediately via Windows Update or WSUS to patch vulnerable builds: upgrade Server 2016 to build 10.0.14393.9060 or later, Server 2019 to 10.0.17763.8644 or later, Server 2022 to 10.0.20348.5020 or later, Server 2022 23H2 to 10.0.25398.2274 or later, and Server 2025 to 10.0.26100.32690 or later. Patches available through Microsoft Update Catalog and MSRC update guide at https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-27928. As interim mitigation where patching is delayed, consider network segmentation to restrict remote access to Windows Hello authentication endpoints, implement additional authentication factors beyond Hello (certificate-based smartcard auth), and monitor authentication logs for anomalous Hello validation failures or unexpected network-sourced authentication attempts. Review Windows Hello for Business deployment policies to ensure least-privilege access and certificate validation strictness.
Same weakness CWE-20 – Improper Input Validation
View allSame technique Authentication Bypass
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External POC / Exploit Code
Leaving vuln.today