Description
Out-of-bounds read in Windows Schannel allows an authorized attacker to disclose information over a network.
Published: 2026-07-14
Score: 8.1 High
EPSS: 1.1% Low
KEV: No
Impact: n/a
Action: n/a
AI Analysis

Impact

The vulnerability is an out‑of‑bounds read in the Schannel component of the Windows operating system. An authenticated attacker with network access can send crafted TLS traffic to a target system, allowing the read to expose data that is transmitted over the secure channel. Because the flaw involves reading beyond array boundaries, it may leak sensitive data such as credentials, cryptographic material, or other confidential information, though it does not permit code execution or denial of service.

Affected Systems

Microsoft Windows 10 versions 1607, 1809, 21H2, and 22H2; Windows 11 versions 24H2, 25H2, and 26H1; and Windows Server editions 2012, 2012 R2, 2016, 2019, 2022, and 2025, including their core installations. These systems run on x86, x64, and arm64 architectures as specified by the listed CPE strings.

Risk and Exploitability

With a CVSS score of 8.1 the flaw is assessed as high severity. The EPSS score of 1 % indicates that while exploitation is unlikely, it is possible, and the vulnerability is not currently listed in the CISA KEV catalog. The attack requires an authenticated or otherwise authorized user who can initiate TLS traffic toward the victim; the out‑of‑bounds read then reveals portions of that traffic. Consequently, the principal risk is the accidental or purposeful disclosure of proprietary or personal data rather than compromise of the operating system.

Generated by OpenCVE AI on July 31, 2026 at 06:31 UTC.

Remediation

No vendor fix or workaround currently provided.

OpenCVE Recommended Actions

  • Apply the Microsoft security update for CVE‑2026‑56186 via Windows Update or the Microsoft Security Response Center advisory.
  • Reconfigure Schannel to disable SSL v2 and SSL v3, enforce TLS 1.2 or higher, and limit cipher suites to secure options, thereby reducing the window for the out‑of‑bounds read.
  • Restrict which accounts can initiate or use TLS connections by applying the principle of least privilege to Schannel‑dependent services and limiting network access to trusted hosts.

Generated by OpenCVE AI on July 31, 2026 at 06:31 UTC.

Tracking

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Advisories

No advisories yet.

History

Tue, 14 Jul 2026 19:30:00 +0000

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}


Tue, 14 Jul 2026 17:45:00 +0000

Type Values Removed Values Added
Description Out-of-bounds read in Windows Schannel allows an authorized attacker to disclose information over a network.
Title Windows Secure Channel Information Disclosure Vulnerability
First Time appeared Microsoft
Microsoft windows 10 1607
Microsoft windows 10 1809
Microsoft windows 10 21h2
Microsoft windows 10 22h2
Microsoft windows 11 24h2
Microsoft windows 11 25h2
Microsoft windows 11 26h1
Microsoft windows Server 2012
Microsoft windows Server 2012 R2
Microsoft windows Server 2016
Microsoft windows Server 2019
Microsoft windows Server 2022
Microsoft windows Server 2025
Weaknesses CWE-125
CPEs cpe:2.3:o:microsoft:windows_10_1607:*:*:*:*:*:*:x86:*
cpe:2.3:o:microsoft:windows_10_1809:*:*:*:*:*:*:x86:*
cpe:2.3:o:microsoft:windows_10_21H2:*:*:*:*:*:*:x86:*
cpe:2.3:o:microsoft:windows_10_22H2:*:*:*:*:*:*:x64:*
cpe:2.3:o:microsoft:windows_11_24H2:*:*:*:*:*:*:arm64:*
cpe:2.3:o:microsoft:windows_11_25H2:*:*:*:*:*:*:arm64:*
cpe:2.3:o:microsoft:windows_11_26H1:*:*:*:*:*:*:x64:*
cpe:2.3:o:microsoft:windows_server_2012:*:*:*:*:*:*:x64:*
cpe:2.3:o:microsoft:windows_server_2012_R2:*:*:*:*:*:*:x64:*
cpe:2.3:o:microsoft:windows_server_2016:*:*:*:*:*:*:*:*
cpe:2.3:o:microsoft:windows_server_2019:*:*:*:*:*:*:*:*
cpe:2.3:o:microsoft:windows_server_2022:*:*:*:*:*:*:*:*
cpe:2.3:o:microsoft:windows_server_2025:*:*:*:*:*:*:*:*
Vendors & Products Microsoft
Microsoft windows 10 1607
Microsoft windows 10 1809
Microsoft windows 10 21h2
Microsoft windows 10 22h2
Microsoft windows 11 24h2
Microsoft windows 11 25h2
Microsoft windows 11 26h1
Microsoft windows Server 2012
Microsoft windows Server 2012 R2
Microsoft windows Server 2016
Microsoft windows Server 2019
Microsoft windows Server 2022
Microsoft windows Server 2025
References
Metrics cvssV3_1

{'score': 8.1, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H/E:U/RL:O/RC:C'}


Subscriptions

Microsoft Windows 10 1607 Windows 10 1809 Windows 10 21h2 Windows 10 22h2 Windows 11 24h2 Windows 11 25h2 Windows 11 26h1 Windows Server 2012 Windows Server 2012 R2 Windows Server 2016 Windows Server 2019 Windows Server 2022 Windows Server 2025
cve-icon MITRE

Status: PUBLISHED

Assigner: microsoft

Published:

Updated: 2026-08-03T22:57:40.280Z

Reserved: 2026-06-19T13:54:04.006Z

Link: CVE-2026-56186

cve-icon Vulnrichment

Updated: 2026-07-14T18:49:37.012Z

cve-icon NVD

No data.

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

Updated: 2026-07-31T06:45:03Z

Weaknesses