CVE-2026-85818: Windows Schannel Spoofing Vulnerability
Improper verification of cryptographic signature in Windows Schannel allows an unauthorized attacker to perform spoofing over a network.
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Upgrade
Upgrade to a fixed release to a version that resolves this vulnerability.
Fixed in 10.0.22631.7652Patch KB5126653 - Upgrade
Upgrade to a fixed release to a version that resolves this vulnerability.
Fixed in 10.0.28000.3231Patch KB5127646 - Upgrade
Upgrade to a fixed release to a version that resolves this vulnerability.
Fixed in 10.0.26100.9711Patch KB5127648 - Upgrade
Upgrade to a fixed release to a version that resolves this vulnerability.
Fixed in 10.0.26200.9711Patch KB5127648 - Upgrade
Upgrade to a fixed release to a version that resolves this vulnerability.
Fixed in 10.0.26100.33650Patch KB5126646 - Upgrade
Upgrade to a fixed release to a version that resolves this vulnerability.
Fixed in 10.0.20348.5761Patch KB5126655 - Upgrade
Upgrade to a fixed release to a version that resolves this vulnerability.
Fixed in 10.0.26300.9711Patch KB5127648
Event History
Frequently Asked Questions
Which systems should be prioritized for assessment?
Assess deployments of Microsoft Windows 11, Windows Server 2022, and Windows Server 2025 that use Schannel for network-facing or network-accessible communications. The vulnerability is remotely reachable over a network and does not require prior privileges or user interaction.
What does an attacker need to exploit this issue?
An attacker must be able to reach the affected Schannel service over the network. Exploitation has high attack complexity, but the provided data indicates no authentication, privileges, or user interaction are required.
What is the likely impact if exploitation succeeds?
The issue allows spoofing because Schannel improperly verifies a cryptographic signature. The supplied severity vector rates confidentiality, integrity, and availability impact as high, with scope changed.