Severity by source
AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Local vector and low complexity with an existing low-privileged account (AV:L/AC:L/PR:L), no interaction, yielding SYSTEM-level full C/I/A impact in an unchanged scope.
Primary rating from Vendor (microsoft).
CVSS VectorVendor: microsoft
Lifecycle Timeline
2DescriptionCVE.org
Deserialization of untrusted data in Windows Wireless Wide Area Network Service allows an authorized attacker to elevate privileges locally.
AnalysisAI
Local privilege escalation in the Windows Wireless Wide Area Network Service (WwanSvc) lets an authenticated low-privileged user elevate to SYSTEM by delivering crafted serialized data that the service deserializes unsafely (CWE-502). Reported by Microsoft, it affects a broad range of Windows 10, Windows 11, and Windows Server builds and carries CVSS 7.8 with high confidentiality, integrity, and availability impact. No public exploit is identified at time of analysis and it is not in CISA KEV, but a vendor patch is available.
Technical ContextAI
The affected component is the Windows Wireless Wide Area Network Service (WwanSvc), the OS service that manages cellular/mobile broadband (WWAN) connectivity on Windows. The root cause is CWE-502, deserialization of untrusted data: the service reconstructs objects from attacker-influenced serialized input without adequately validating type or content, allowing manipulation of the object graph to reach dangerous code paths or corrupt state within the privileged service context. Per the CPE data, the vulnerable code ships across microsoft:windows_10 (1607, 1809, 21H2, 22H2), microsoft:windows_11 (24H2, 25H2, 26H1), and Windows Server 2016, 2019, and 2025 including Server Core installations, indicating shared library code common to modern Windows servicing branches.
RemediationAI
Apply the Microsoft security update for CVE-2026-50509 for your specific Windows build; a vendor patch is available and the authoritative per-product fixed versions are listed at https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-50509 (Patch available per vendor advisory). Because the flaw is a local elevation-of-privilege in the WWAN service, prioritize patching multi-user systems, terminal/RDP hosts, and any machine where untrusted users hold interactive or low-privilege access. Where immediate patching is not possible, a specific compensating control is to stop and disable the Wireless WAN Service (WwanSvc) on systems that do not use cellular/mobile broadband hardware, which removes the reachable attack surface at the cost of losing WWAN/cellular connectivity; additionally, tighten local account controls to limit which users can run code on affected hosts. Verify patch deployment through update-management reporting rather than assuming coverage.
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Same weakness CWE-502 – Deserialization of Untrusted Data
View allSame technique Deserialization
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External POC / Exploit Code
Leaving vuln.today
EUVD-2026-44115
GHSA-4jqm-4jm7-mqg5