Windows SMB Client Information Disclosure Vulnerability
MonitorCVSS 5.5CVE-2026-69618Sep 8, 2026
Microsoft
IT in OT - Windows Server and Active Directory are widely deployed in OT environments
Attack path
Attack VectorLocal
Auth RequiredLow
ComplexityLow
User InteractionNone needed
Summary
Out-of-bounds read in Windows SMB Client allows an authorized local attacker to disclose information. The vulnerability occurs when the SMB client processes certain network responses and reads memory beyond intended boundaries, potentially exposing sensitive data to an attacker with local access and credentials on the affected system.
What this means
What could happen
An authorized user on a Windows system could read sensitive information from system memory, such as cached credentials, configuration data, or other protected data stored in memory. This information disclosure could enable privilege escalation or lateral movement within your network.
Who's at risk
Windows IT infrastructure running Windows 10 (versions 1607, 1809, 21H2, 22H2) or Windows 11 (versions 23H2, 24H2, 25H2, 26H1), and Windows Server 2016, 2019, 2022, or 2025. Any organization using these systems for file sharing, network operations, or general computing is affected. This includes both standard and Server Core installations.
How it could be exploited
An attacker with local user credentials could trigger the out-of-bounds read by interacting with the SMB client on the affected system, potentially through file share operations or network communication that causes the SMB client to access memory beyond its intended bounds and leak information the attacker should not have access to.
Prerequisites
- Local user account credentials on the affected Windows system
- Ability to interact with SMB client functionality (file share access or network operations)
Local authentication requiredLow complexity attackInformation disclosure only (no code execution or availability impact)
Exploitability
Unlikely to be exploited — EPSS score 0.4%
Affected products (26)
26 with fix
ProductAffected VersionsFix Status
Remediation & Mitigation
0/1
Schedule — requires maintenance window
0/1Patching may require device reboot — plan for process interruption
HOTFIXApply the 2026-Sep Windows security update or later to all affected Windows 10 and Windows Server systems
CVEs (1)
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