EUVD-2026-43897
GHSA-r43c-rm8g-w8c6
Severity by source
AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Local privilege escalation requiring an existing low-privileged account (PR:L, AV:L), no user interaction, yielding full SYSTEM-level compromise, so C/I/A all High.
Primary rating from Vendor (microsoft).
CVSS VectorVendor: microsoft
Lifecycle Timeline
2DescriptionCVE.org
Improper access control in Windows Operating Systems allows an authorized attacker to elevate privileges locally.
AnalysisAI
Elevation of privilege in Microsoft Windows (Windows 10 1809/21H2/22H2, Windows 11 24H2/25H2/26H1, and Windows Server 2019/2022/2025) allows a locally authenticated attacker to escalate to higher privileges via an improper access control weakness (CWE-284). An attacker who already holds a low-privilege foothold on the host can gain full confidentiality, integrity, and availability impact over the system. No public exploit identified at time of analysis, though the flaw was reported by Microsoft and a vendor patch is available.
Technical ContextAI
The affected component is the core Windows operating system across both client (Windows 10/11) and server (Server 2019/2022/2025, including Server Core) editions, as confirmed by the Microsoft CPE list. The root cause is CWE-284 (Improper Access Control), meaning a securable Windows resource or operation fails to correctly enforce authorization, allowing a principal with limited rights to perform an action reserved for a more privileged context. Consistent with the CVSS local vector and Server Core coverage, this is an OS-level authorization boundary failure rather than a remote network service flaw; the vendor 'Authentication Bypass' tag further suggests the access-control gate can be circumvented rather than requiring credential theft.
RemediationAI
Patch available per vendor advisory: apply the Microsoft security update for the affected OS via the MSRC entry at https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-50335, which lists the exact patched build for each Windows 10/11 and Windows Server release; deploy through Windows Update, WSUS, or your managed pipeline (SCCM/Intune) as part of the current Patch Tuesday cycle. Exact fixed build numbers are not included in the input and must be read from the MSRC page, so do not substitute an invented version. Because this is a local elevation-of-privilege flaw, compensating controls while patching center on limiting who can execute code locally: enforce least privilege by removing standard users from local Administrators where possible, restrict interactive and RDP logon rights on servers to administrators only, and apply application allowlisting (WDAC/AppLocker) to block the unprivileged code an attacker would run to trigger the flaw - with the trade-off that allowlisting requires tuning to avoid breaking legitimate applications. These controls raise the bar for gaining and abusing the initial foothold but do not remediate the underlying access-control defect, so patching remains mandatory.
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Same weakness CWE-284 – Improper Access Control
View allSame technique Authentication Bypass
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External POC / Exploit Code
Leaving vuln.today