---
id: CVE-2026-77889
title: >-
  Access of resource using incompatible type ('type confusion') in Windows DHCP
  Server allows an unauthorized attacker to deny service over a network.
summary: >-
  Access of resource using incompatible type ('type confusion') in Windows DHCP
  Server allows an unauthorized attacker to deny service over a network.
severity: high
cvss: 7.5
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H'
cwe:
  - CWE-843
vendor: microsoft
product: windows_10_1607
affected:
  - windows_10_1607 < 10.0.14393.9512
  - windows_10_1809 < 10.0.17763.9245
  - windows_server_2012
  - windows_server_2012 = r2
  - windows_server_2016 < 10.0.14393.9512
  - windows_server_2019 < 10.0.17763.9245
  - windows_server_2022 < 10.0.20348.5622
  - windows_server_2025 < 10.0.26100.33438
patched:
  - windows_10_1607 10.0.14393.9512
  - windows_10_1809 10.0.17763.9245
  - windows_server_2016 10.0.14393.9512
  - windows_server_2019 10.0.17763.9245
  - windows_server_2022 10.0.20348.5622
  - windows_server_2025 10.0.26100.33438
published: '2026-09-08'
updated: '2026-09-16'
sourceUpdated: '2026-09-16T15:09:27.697'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-77889'
references:
  - url: 'https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-77889'
    label: secure@microsoft.com
tags:
  - nvd
  - cve.org
epss: 0.00852
epssPercentile: 0.56753
ssvc:
  exploitation: none
  automatable: 'yes'
  technicalImpact: partial
  timestamp: '2026-09-08T18:56:02.498196Z'
ingestedAt: '2026-09-08T19:08:49.628Z'
---

## Overview

Access of resource using incompatible type ('type confusion') in Windows DHCP Server allows an unauthorized attacker to deny service over a network.

## Affected

- `windows_10_1607 < 10.0.14393.9512`
- `windows_10_1809 < 10.0.17763.9245`
- `windows_server_2012`
- `windows_server_2012 = r2`
- `windows_server_2016 < 10.0.14393.9512`
- `windows_server_2019 < 10.0.17763.9245`
- `windows_server_2022 < 10.0.20348.5622`
- `windows_server_2025 < 10.0.26100.33438`

## Remediation

Upgrade past the affected range:

- `windows_10_1607 10.0.14393.9512`
- `windows_10_1809 10.0.17763.9245`
- `windows_server_2016 10.0.14393.9512`
- `windows_server_2019 10.0.17763.9245`
- `windows_server_2022 10.0.20348.5622`
- `windows_server_2025 10.0.26100.33438`