Vulnerability · Published Oct 13, 2026 · Assigned by microsoft
CVE-2026-85818Windows Schannel Spoofing Vulnerability
Critical 9.0
In plain English
A critical-severity security flaw in Windows 11 version 23H2 from Microsoft. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.4% (higher than 36% of all known vulnerabilities).
Severity (CVSS 3.1)9.0Critical
Exploit odds (30 days)0.4%top 64.1% of all CVEs
Exploited in the wildNo reportsCISA SSVC: none
Attack toolingNoneno public tooling known
Official description
Improper verification of cryptographic signature in Windows Schannel allows an unauthorized attacker to perform spoofing over a network.
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| Microsoft | Windows 11 version 23H2 | 10.0.22631.0 – before 10.0.22631.7652 |
| Microsoft | Windows 11 Version 23H2 | 10.0.22631.0 – before 10.0.22631.7652 |
| Microsoft | Windows 11 Version 24H2 | 10.0.26100.0 – before 10.0.26100.9711 |
| Microsoft | Windows 11 Version 25H2 | 10.0.26200.0 – before 10.0.26200.9711 |
| Microsoft | Windows 11 version 26H1 | 10.0.28000.0 – before 10.0.28000.3231 |
| Microsoft | Windows 11 Version 26H2 | 10.0.26300.0 – before 10.0.26300.9711 |
| Microsoft | Windows Server 2022 | 10.0.20348.0 – before 10.0.20348.5761 |
| Microsoft | Windows Server 2025 | 10.0.26100.0 – before 10.0.26100.33650 |
| Microsoft | Windows Server 2025 (Server Core installation) | 10.0.26100.0 – before 10.0.26100.33650 |
Weakness: CWE-347 · Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:H/E:U/RL:O/RC:C
References
- Windows Schannel Spoofing Vulnerability vendor-advisory, patch