EUVD-2026-56604
GHSA-pwpm-f3h4-8mvh
Severity by source
AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Local vector confirmed by description; PR:L reflects required authenticated local account; full C/I/A matches SYSTEM-level privilege escalation with no scope change.
Primary rating from Vendor (microsoft).
CVSS VectorVendor: microsoft
Lifecycle Timeline
3DescriptionCVE.org
Missing authentication for critical function in Windows RPC API allows an authorized attacker to elevate privileges locally.
AnalysisAI
Local privilege escalation in the Windows RPC API exploits a missing authentication gate on a critical function (CWE-306), enabling any low-privileged authenticated local user to attain SYSTEM-level control across a sweeping range of Windows 10, Windows 11, and Windows Server editions from 2012 through 2025. The CVSS vector (AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H) confirms low-complexity exploitation requiring only a standard user account with no user interaction. No public exploit code is identified at time of analysis, and CISA SSVC rates current exploitation status as none, though technical impact is rated total.
Technical ContextAI
The Windows Remote Procedure Call (RPC) API is a core inter-process communication framework built into every supported Windows release, enabling both local and network service calls between processes. CWE-306 (Missing Authentication for Critical Function) identifies the root cause: a code path within the RPC subsystem that performs a privileged operation fails to enforce the expected authentication or authorization check before execution, allowing callers with only low OS privileges to invoke it. Affected platforms span client and server SKUs: Windows 10 versions 1607, 1809, 21H2, and 22H2; Windows 11 versions 24H2, 25H2, and 26H1; Windows Server 2012, 2012 R2, 2016, 2019, 2022, and 2025, including all corresponding Server Core installations, as confirmed by EUVD-2026-56604. Because RPC is enabled by default and underpins countless Windows services, no non-standard configuration is needed to expose the vulnerable code path.
RemediationAI
Apply the vendor-released patch via Windows Update, Microsoft Update Catalog, or WSUS targeting the fixed build for each affected version: Windows 10 1607/Server 2016 to 10.0.14393.9234 or later, Windows 10/Server 2019 1809 to 10.0.17763.8880 or later, Windows 10 21H2 to 10.0.19044.7417 or later, Windows 10 22H2 to 10.0.19045.7417 or later, Windows 11 24H2/Server 2025 to 10.0.26100.9168 or 10.0.26100.32995 or later, Windows 11 25H2 to 10.0.26200.9168 or later, Windows 11 26H1 to 10.0.28000.2269 or later, Windows Server 2022 to 10.0.20348.5499 or later, and legacy Server 2012/2012 R2 to 6.2.9200.26132 or 6.3.9600.23228 or later (the latter only via Extended Security Updates). Consult the full patch matrix at https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-42976. Where immediate patching is infeasible, restrict local interactive logon and Remote Desktop access to only explicitly trusted administrative accounts - this raises the bar by limiting which identities can reach the vulnerable RPC endpoint locally, but note it does not eliminate the flaw and any account with local logon rights remains a potential attacker. Application of Credential Guard and Privileged Access Workstation (PAW) architectures can further constrain privilege escalation blast radius but are not substitutes for patching.
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External POC / Exploit Code
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