---
id: CVE-2026-85818
title: >-
  Improper verification of cryptographic signature in Windows Schannel allows an
  unauthorized attacker to perform spoofing over a network.
summary: >-
  Improper verification of cryptographic signature in Windows Schannel allows an
  unauthorized attacker to perform spoofing over a network.
severity: critical
cvss: 9
cvssVector: 'CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:H'
cwe:
  - CWE-347
vendor: microsoft
product: windows_11_23h2
affected:
  - windows_11_23h2 < 10.0.22631.7652
  - windows_11_24h2 < 10.0.26100.9711
  - windows_11_25h2 < 10.0.26200.9711
  - windows_11_26h1 < 10.0.28000.3231
  - windows_11_26h2 < 10.0.26300.9711
  - windows_server_2022 < 10.0.20348.5761
  - windows_server_2025 < 10.0.26100.33650
patched:
  - windows_11_23h2 10.0.22631.7652
  - windows_11_24h2 10.0.26100.9711
  - windows_11_25h2 10.0.26200.9711
  - windows_11_26h1 10.0.28000.3231
  - windows_11_26h2 10.0.26300.9711
  - windows_server_2022 10.0.20348.5761
  - windows_server_2025 10.0.26100.33650
published: '2026-10-13'
updated: '2026-10-16'
sourceUpdated: '2026-10-16T19:58:02.273'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-85818'
references:
  - url: 'https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-85818'
    label: secure@microsoft.com
tags:
  - nvd
  - cve.org
ssvc:
  exploitation: none
  automatable: 'no'
  technicalImpact: total
  timestamp: '2026-10-13T22:16:24.873537Z'
epss: 0.00414
epssPercentile: 0.35543
ingestedAt: '2026-10-13T19:43:29.173Z'
---

## Overview

Improper verification of cryptographic signature in Windows Schannel allows an unauthorized attacker to perform spoofing over a network.

## Affected

- `windows_11_23h2 < 10.0.22631.7652`
- `windows_11_24h2 < 10.0.26100.9711`
- `windows_11_25h2 < 10.0.26200.9711`
- `windows_11_26h1 < 10.0.28000.3231`
- `windows_11_26h2 < 10.0.26300.9711`
- `windows_server_2022 < 10.0.20348.5761`
- `windows_server_2025 < 10.0.26100.33650`

## Remediation

Upgrade past the affected range:

- `windows_11_23h2 10.0.22631.7652`
- `windows_11_24h2 10.0.26100.9711`
- `windows_11_25h2 10.0.26200.9711`
- `windows_11_26h1 10.0.28000.3231`
- `windows_11_26h2 10.0.26300.9711`
- `windows_server_2022 10.0.20348.5761`
- `windows_server_2025 10.0.26100.33650`