EUVD-2026-43988
GHSA-5mhp-vr58-c5wv
Severity by source
AV:L/AC:L/PR:L/UI:N/S:U/C:L/I:H/A:N
Local-only exploitation by low-privileged OS user; DNS tampering yields high integrity impact with no availability or significant confidentiality consequence.
Primary rating from Vendor (microsoft).
CVSS VectorVendor: microsoft
Lifecycle Timeline
2DescriptionCVE.org
Missing authentication for critical function in Microsoft Windows DNS allows an authorized attacker to perform tampering locally.
AnalysisAI
Missing authentication enforcement in the Microsoft Windows DNS component allows a low-privileged local attacker to tamper with DNS configuration or records without requiring elevated credentials. Affected platforms span Windows 10 (versions 1809 through 22H2), Windows 11 (versions 24H2 through 26H1), and Windows Server 2019 through 2025 - a broad deployment footprint across enterprise environments. No public exploit code has been identified and CISA SSVC rates exploitation as 'none' with partial technical impact, but the high integrity impact (CVSS I:H) warrants attention in multi-user environments and on DNS server infrastructure where record integrity is critical.
Technical ContextAI
The root cause is CWE-306 (Missing Authentication for Critical Function), meaning the Windows DNS subsystem exposes one or more privileged operations - such as DNS record modification or configuration changes - without enforcing authentication checks appropriate to those operations. On Windows Server roles (Server 2019, 2022, 2025), this has higher impact as the DNS Server service manages authoritative zone data; on Windows 10/11 client builds (confirmed via CPE: cpe:2.3:a:microsoft:windows_10_version_1809 through cpe:2.3:a:microsoft:windows_11_version_26h1), the DNS client subsystem is also implicated. The CVSS vector (AV:L/AC:L/PR:L/UI:N/S:U) confirms exploitation is local-only, requires no elevated OS privileges beyond a standard authenticated user account, and involves no user interaction. The lack of authentication enforcement on a critical DNS function is the singular root cause - not a logic error or memory corruption class issue.
RemediationAI
Apply Microsoft's released patches via Windows Update or WSUS, targeting the following minimum fixed builds confirmed by EUVD-2026-43988: Windows 10 1809 and Server 2019 to 10.0.17763.9020 or later; Windows 10 21H2 to 10.0.19044.7548 or later; Windows 10 22H2 to 10.0.19045.7548 or later; Windows 11 24H2 to 10.0.26100.8875 or later; Windows 11 25H2 to 10.0.26200.8875 or later; Windows 11 26H1 to 10.0.28000.2269 or later; Windows Server 2022 to 10.0.20348.5386 or later; Windows Server 2025 to 10.0.26100.33158 or later. Full advisory is at https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-49174. As a compensating control where immediate patching is not feasible on DNS server infrastructure, restrict local logon rights (via Group Policy: 'Allow log on locally') to Domain Admins and DNS Admins only, eliminating standard-user local access entirely - note this will impact helpdesk or monitoring accounts requiring interactive local sessions. Additionally, audit DNS zone permissions and enable DNS audit logging (Windows DNS Server audit events) to detect unauthorized record changes in the interim.
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External POC / Exploit Code
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