EUVD-2026-44245
GHSA-9hmw-8q29-cpgf
Severity by source
AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H
Network-reachable, low-complexity, authenticated (PR:L) over-read yielding high confidentiality loss; I:N and A:N since the description confirms only information disclosure, not integrity or availability impact.
Primary rating from Vendor (microsoft).
CVSS VectorVendor: microsoft
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H
Lifecycle Timeline
2DescriptionCVE.org
Out-of-bounds read in Windows Schannel allows an authorized attacker to disclose information over a network.
AnalysisAI
Information disclosure in Microsoft Windows Schannel (the Secure Channel TLS/SSL provider) lets an authenticated, network-adjacent attacker read memory beyond an allocated buffer and leak sensitive data across a network connection. The flaw spans nearly the entire supported Windows family - Windows 10 (1607 through 22H2), Windows 11 (24H2/25H2/26H1), and Windows Server 2012 through 2025. …
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Attack ChainAIDerived
Hypothetical attack flow derived from CVE metadata
Vulnerability AssessmentAI
| Exploitation | Exploitation requires network access to a Windows service that uses Schannel for TLS/SSL and, per the CVSS vector's PR:L, an authenticated or otherwise authorized attacker - this is not remote-unauthenticated. … Additional conditions and limiting factors are described in the full assessment. |
| Risk Assessment | The CVSS 3.1 score of 8.1 (AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H) indicates a network-reachable flaw of low complexity requiring some level of privilege (PR:L, i.e. … Full risk analysis with EPSS, KEV, and SSVC signal comparison available after sign-in. |
| Exploit Scenario | An attacker who already holds valid credentials or an authenticated session to a Windows service that terminates TLS via Schannel sends crafted protocol data over the network, causing Schannel to over-read process memory and return leaked bytes (potentially session material or other secrets) in its response. Given AV:N and AC:L, the interaction is straightforward once authenticated, but no public exploit code has been identified at time of analysis. |
| Remediation | Apply the Microsoft security update for your specific Windows build - Patch available per vendor advisory; consult https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-56186 for the exact patched KB and build number for each affected SKU (exact fix version is not restated in the provided data, so pull it from MSRC per your OS). … Detailed patch versions, workarounds, and compensating controls in full report. |
Recommended ActionAI
Within 24 hours, identify and inventory all Windows 10 (versions 1607-22H2), Windows 11 (versions 24H2, 25H2, 26H1), and Windows Server 2012-2025 systems and confirm vendor patch availability from Microsoft Security Updates. …
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External POC / Exploit Code
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