---
id: CVE-2026-72940
title: >-
  Heap-based buffer overflow in Windows Schannel allows an unauthorized attacker
  to execute code over a network.
summary: >-
  Heap-based buffer overflow in Windows Schannel allows an unauthorized attacker
  to execute code over a network.
severity: high
cvss: 8.8
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H'
cwe:
  - CWE-122
vendor: microsoft
product: windows_11_23h2
affected:
  - windows_11_23h2 < 10.0.22631.7582
  - windows_11_24h2 < 10.0.26100.9445
  - windows_11_25h2 < 10.0.26200.9445
  - windows_11_26h1 < 10.0.28000.2954
  - windows_server_2022 < 10.0.20348.5622
  - windows_server_2025 < 10.0.26100.33438
patched:
  - windows_11_23h2 10.0.22631.7582
  - windows_11_24h2 10.0.26100.9445
  - windows_11_25h2 10.0.26200.9445
  - windows_11_26h1 10.0.28000.2954
  - windows_server_2022 10.0.20348.5622
  - windows_server_2025 10.0.26100.33438
published: '2026-09-08'
updated: '2026-09-22'
sourceUpdated: '2026-09-22T11:49:47.797'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-72940'
references:
  - url: 'https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-72940'
    label: secure@microsoft.com
tags:
  - nvd
  - cve.org
epss: 0.00819
epssPercentile: 0.55346
ssvc:
  exploitation: none
  automatable: 'no'
  technicalImpact: total
  timestamp: '2026-09-09T18:37:00.612797Z'
ingestedAt: '2026-09-08T19:08:49.624Z'
---

## Overview

Heap-based buffer overflow in Windows Schannel allows an unauthorized attacker to execute code over a network.

## Affected

- `windows_11_23h2 < 10.0.22631.7582`
- `windows_11_24h2 < 10.0.26100.9445`
- `windows_11_25h2 < 10.0.26200.9445`
- `windows_11_26h1 < 10.0.28000.2954`
- `windows_server_2022 < 10.0.20348.5622`
- `windows_server_2025 < 10.0.26100.33438`

## Remediation

Upgrade past the affected range:

- `windows_11_23h2 10.0.22631.7582`
- `windows_11_24h2 10.0.26100.9445`
- `windows_11_25h2 10.0.26200.9445`
- `windows_11_26h1 10.0.28000.2954`
- `windows_server_2022 10.0.20348.5622`
- `windows_server_2025 10.0.26100.33438`