EUVD-2026-56664
GHSA-3xxp-88xx-wwq3
Severity by source
AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
Network-reachable SMB client flaw requiring no attacker credentials or user interaction; impact strictly limited to memory disclosure with no integrity or availability consequence.
Primary rating from Vendor (microsoft).
CVSS VectorNVD
Lifecycle Timeline
7DescriptionNVD
Out-of-bounds read in Windows SMB Client allows an unauthorized attacker to disclose information over a network.
AnalysisAI
Remote information disclosure in the Windows SMB Client affects every actively-supported Windows 10, Windows 11, and Windows Server release from 2016 through 2025, exposing potentially sensitive memory contents to unauthenticated network attackers via a CWE-125 out-of-bounds read (CVSS 7.5). The flaw resides in the SMB client stack and is triggered when a vulnerable Windows host processes a crafted response from an attacker-controlled SMB server, requiring no authentication or user interaction from the attacker's perspective. …
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Attack ChainAIDerived
Hypothetical attack flow derived from CVE metadata
Vulnerability AssessmentAI
| Exploitation | Exploitation requires the attacker to operate a network-reachable SMB server and to cause the target Windows host's SMB client to initiate a connection to that server. … Additional conditions and limiting factors are described in the full assessment. |
| Risk Assessment | The CVSS 7.5 score (AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N) positions this as high-severity with a fully unauthenticated network attack path, but multiple contextual signals argue for calibrated urgency rather than emergency response. … 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 | Apply the Microsoft-released patch through Windows Update, WSUS, or an endpoint management platform targeting the following minimum fixed builds confirmed by EUVD-2026-56664: Windows 10 1607 and Server 2016 to 10.0.14393.9418 or later, Windows 10 1809 and Server 2019 to 10.0.17763.9115 or later, Windows 10 21H2 to 10.0.19044.7663 or later, Windows 10 22H2 to 10.0.19045.7663 or later, Windows Server 2022 to 10.0.20348.5499 or later, Windows 11 23H2 to 10.0.22631.7517 or later, Windows 11 24H2 to 10.0.26100.9168 or later, Windows Server 2025 and Server Core to 10.0.26100.33296 or later, Windows 11 25H2 to 10.0.26200.9168 or later, and Windows 11 26H1 to 10.0.28000.2704 or later. … Detailed patch versions, workarounds, and compensating controls in full report. |
Recommended ActionAI
Within 24 hours, inventory all Windows 10, Windows 11, and Windows Server 2016-2025 systems and identify which face direct network-accessible SMB exposure; simultaneously begin testing the vendor-released patch in an isolated lab environment to confirm compatibility with critical applications and services. …
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External POC / Exploit Code
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