EUVD-2026-56740
GHSA-jfm8-7w64-f4rm
Severity by source
AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N
Attacker controls a remote SMB server (AV:N, PR:N); user must connect to it (UI:R, AC:L); only memory disclosure results with no integrity or availability impact.
Primary rating from Vendor (microsoft).
CVSS VectorVendor: microsoft
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N
Lifecycle Timeline
3DescriptionCVE.org
Buffer over-read in Windows SMB Client allows an unauthorized attacker to disclose information over a network.
AnalysisAI
Information disclosure via a buffer over-read in the Windows SMB Client component affects a broad spectrum of Microsoft Windows desktop and server editions, from Windows Server 2012 through Windows 11 25H2. An attacker who controls a malicious SMB server and induces a target Windows user to connect to it can trigger the client to read beyond allocated memory buffer boundaries, leaking potentially sensitive process memory contents across the network. …
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Attack ChainAIDerived
Hypothetical attack flow derived from CVE metadata
Vulnerability AssessmentAI
| Exploitation | Exploitation requires that a Windows user actively interacts with a resource controlled by the attacker - specifically, the SMB Client must initiate a connection to a malicious SMB server (UI:R per CVSS vector). … Additional conditions and limiting factors are described in the full assessment. |
| Risk Assessment | The CVSS 3.1 vector (AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N) scores 6.5 and captures a meaningful but structurally bounded risk: network-reachable, low-complexity exploitation with no attacker privileges required, but user interaction is a necessary prerequisite that materially prevents automated mass exploitation. … Full risk analysis with EPSS, KEV, and SSVC signal comparison available after sign-in. |
| Exploit Scenario | An attacker stands up a malicious SMB server on a network segment reachable by target Windows systems and crafts specially malformed SMB server responses designed to trigger the buffer over-read in the Windows SMB Client. The attacker then delivers a UNC path link (such as \\attacker-server\share) to a target user via phishing email, a malicious document, or a web page, inducing the user to connect - which causes the Windows SMB Client to process the malicious response, read past the allocated buffer boundary, and leak memory contents back to the attacker over the network. … |
| Remediation | The primary remediation is to apply the Microsoft-released cumulative update that advances affected builds beyond the thresholds confirmed in EUVD-2026-56740: Windows Server 2025 to 10.0.26100.33296, Windows Server 2022 to 10.0.20348.5499, Windows Server 2019 to 10.0.17763.9115, Windows Server 2016 to 10.0.14393.9418, Windows Server 2012 R2 to 6.3.9600.23337, Windows Server 2012 to 6.2.9200.26279, and the corresponding Windows 10/11 client builds listed above. … Detailed patch versions, workarounds, and compensating controls in full report. |
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External POC / Exploit Code
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