CVE-2026-62757

Analyzed Analyzed - Analysis Complete

Improper Cryptographic Signature Verification in Windows Schannel

Publication date: 2026-08-11

Last updated on: 2026-08-16

Assigner: Microsoft Corporation

Description

Improper verification of cryptographic signature in Windows Schannel allows an unauthorized attacker to bypass a security feature over a network.

CVSS Scores

EPSS Scores

Probability:
Percentile:

Meta Information

Published

2026-08-11

Last Modified

2026-08-16

Generated

2026-09-01

AI Q&A

2026-08-12

EPSS Evaluated

2026-08-30

NVD

CVE-2026-62757

EUVD

EUVD-2026-56649

Affected Vendors & Products

Vendor	Product	Version / Range
microsoft	windows_server_2012	r2
microsoft	windows_server_2012	*
microsoft	windows_10_1607	to 10.0.14393.9418 (exc)
microsoft	windows_10_1607	to 10.0.14393.9418 (exc)
microsoft	windows_10_1809	to 10.0.17763.9115 (exc)
microsoft	windows_10_1809	to 10.0.17763.9115 (exc)
microsoft	windows_10_21h2	to 10.0.19044.7663 (exc)
microsoft	windows_10_21h2	to 10.0.19044.7663 (exc)
microsoft	windows_10_21h2	to 10.0.19044.7663 (exc)
microsoft	windows_10_22h2	to 10.0.19045.7663 (exc)
microsoft	windows_10_22h2	to 10.0.19045.7663 (exc)
microsoft	windows_10_22h2	to 10.0.19045.7663 (exc)
microsoft	windows_11_23h2	to 10.0.22631.7517 (exc)
microsoft	windows_11_23h2	to 10.0.22631.7517 (exc)
microsoft	windows_11_24h2	to 10.0.26100.9106 (exc)
microsoft	windows_11_24h2	to 10.0.26100.9106 (exc)
microsoft	windows_11_26h1	to 10.0.28000.2704 (exc)
microsoft	windows_11_26h1	to 10.0.28000.2704 (exc)
microsoft	windows_11_25h2	to 10.0.26200.9106 (exc)
microsoft	windows_11_25h2	to 10.0.26200.9106 (exc)
microsoft	windows_server_2016	to 10.0.14393.9418 (exc)
microsoft	windows_server_2019	to 10.0.17763.9115 (exc)
microsoft	windows_server_2022	to 10.0.20348.5440 (exc)
microsoft	windows_server_2025	to 10.0.26100.33222 (exc)

Helpful Resources

Exploitability

CWE

KEV

CWE ID	Description
CWE-347	The product does not verify, or incorrectly verifies, the cryptographic signature for data.

Attack-Flow Graph

Executive Summary

This vulnerability involves improper verification of cryptographic signatures in Windows Schannel. An unauthorized attacker can bypass a security feature over a network due to this flaw.

Detection Guidance

Detection of this vulnerability requires monitoring Windows systems for improper cryptographic signature verification in Schannel. Check Windows Event Logs for Schannel-related errors or warnings, particularly under Security and System logs. Use PowerShell commands like Get-WinEvent -LogName 'System' -ProviderName 'Schannel' to review relevant events.

Impact Analysis

An attacker could exploit this to bypass security protections, potentially allowing unauthorized access or actions on affected systems. The impact depends on the specific security feature bypassed.

Compliance Impact

This vulnerability allows bypassing a security feature via improper cryptographic signature verification in Windows Schannel. While not explicitly linked to compliance standards in the provided text, such security feature bypasses could potentially impact adherence to regulations requiring strong cryptographic controls, such as GDPR's data integrity requirements or HIPAA's safeguards for protected health information.

Mitigation Strategies

Apply the latest security updates from Microsoft to patch the improper cryptographic signature verification in Windows Schannel. Monitor Microsoft's advisory for additional guidance.

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