EUVD-2026-56328
GHSA-m4h5-7279-wf6j
Severity by source
AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H
Local session with low-privilege account required; AC:H reflects heap-timing or race-condition dependency typical of double-free exploitation; full triad impact from SYSTEM-level code execution on the vulnerable host.
Primary rating from Vendor (microsoft).
CVSS VectorVendor: microsoft
Lifecycle Timeline
3DescriptionCVE.org
Double free in Windows Network Connection Broker allows an authorized attacker to elevate privileges locally.
AnalysisAI
Privilege escalation via double-free memory corruption in the Windows Network Connection Broker (NCBroker) service affects a broad swath of Microsoft Windows desktop and server releases spanning Windows 10 through Windows 11 26H1 and Windows Server 2012 through Server 2025. An authenticated local attacker with low-privilege access can exploit heap corruption induced by the double-free condition (CWE-415) to elevate privileges to SYSTEM level. …
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Attack ChainAIDerived
Hypothetical attack flow derived from CVE metadata
Vulnerability AssessmentAI
| Exploitation | Exploitation requires a local, authenticated session on the affected Windows system with at minimum a standard (low-privilege) user account - the CVSS vector AV:L/PR:L explicitly rules out remote unauthenticated exploitation. … Additional conditions and limiting factors are described in the full assessment. |
| Risk Assessment | The CVSS 3.1 vector (AV:L/AC:H/PR:L/UI:N) places the realistic exploitation bar as meaningful: the attacker must hold a local, low-privilege session (PR:L), and the high attack complexity (AC:H) implies timing dependencies or race conditions typical of double-free exploitation - reliably triggering the correct heap layout is non-trivial. … Full risk analysis with EPSS, KEV, and SSVC signal comparison available after sign-in. |
| Exploit Scenario | Full exploit scenario with step-by-step reproduction available after sign-in. |
| Remediation | The primary remediation is to apply the Microsoft security update delivered through Windows Update or the Microsoft Update Catalog, patching affected systems to the fixed build versions confirmed in EUVD-2026-56328 and documented at https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-61366. … Detailed patch versions, workarounds, and compensating controls in full report. |
Recommended ActionAI
Within 24 hours, inventory all Windows systems (endpoints, servers, workstations) and identify those running affected versions (Windows 10, 11, 26H1, or Server 2012-2025) to prioritize patching. …
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External POC / Exploit Code
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