EUVD-2026-43954
GHSA-4c2m-fqxw-9gw8
Severity by source
AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Local escalation by an already-authenticated low-privileged user (AV:L, PR:L), no interaction and low complexity (UI:N, AC:L), yielding total SYSTEM compromise (C/I/A:H).
Primary rating from Vendor (microsoft).
CVSS VectorNVD
Lifecycle Timeline
5DescriptionNVD
Missing authentication for critical function in Windows Routing and Remote Access Service (RRAS) allows an authorized attacker to elevate privileges locally.
AnalysisAI
Local privilege escalation in the Windows Routing and Remote Access Service (RRAS) lets an already-authenticated, low-privileged user gain SYSTEM-level control across a broad range of Windows 10, Windows 11, and Windows Server 2012 through 2025 builds. The root cause is a missing authentication check on a critical RRAS function (CWE-306), enabling an authorized attacker to bypass expected authorization and fully compromise confidentiality, integrity, and availability of the host. There is no public exploit identified at time of analysis, EPSS probability is low (0.22%), and CISA SSVC rates current exploitation as none, but the total technical impact and Microsoft-supplied patch make prompt patching worthwhile.
Technical ContextAI
RRAS is a built-in Windows networking role that provides routing, VPN (dial-up, PPTP/L2TP/SSTP/IKEv2), NAT, and remote-access gateway services, running as a privileged system component. The weakness is CWE-306 (Missing Authentication for a Critical Function): a security-sensitive RRAS operation is exposed without verifying that the caller is authorized to invoke it, so a local user who can reach the interface can trigger a privileged action they should not be able to. The CPE set (cpe:2.3:a:microsoft:windows_10_version_1607 through windows_11_version_26h1, plus Windows Server 2012/2012 R2 and, per the EUVD version data, Server 2016/2019/2022/2025 including Server Core installations) indicates the vulnerable RRAS code ships uniformly across the modern Windows codebase rather than in a single edition.
RemediationAI
Apply the Microsoft security update for CVE-2026-50451 via the MSRC advisory (https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-50451), upgrading each affected build to at or above its fixed version - for example Windows 11 24H2 to 10.0.26100.8875, Windows Server 2022 to 10.0.20348.5386, Windows Server 2025 to 10.0.26100.33158, Windows 10 22H2 to 10.0.19045.7548, and Windows Server 2012 R2 to 6.3.9600.23291. Patch status: Patch available per vendor advisory (vendor-released patch confirmed by Microsoft). Where immediate patching is impossible, reduce exposure by disabling the Routing and Remote Access service on hosts that do not need routing/VPN/NAT (Set-Service RemoteAccess -StartupType Disabled; Stop-Service RemoteAccess), accepting the trade-off that dependent VPN, NAT, or routing functionality will stop, and by tightening who can log on locally or via RDP to multi-user servers to shrink the pool of low-privileged accounts that could stage the attack. These are compensating controls only; the update is the definitive fix.
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External POC / Exploit Code
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