---
id: CVE-2021-33745
title: Windows DNS Server Denial of Service Vulnerability
summary: Windows DNS Server Denial of Service Vulnerability
severity: medium
cvss: 6.5
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H'
vendor: microsoft
product: windows_server_2008
affected:
  - windows_server_2008
  - windows_server_2008 = r2
  - windows_server_2012
  - windows_server_2012 = r2
  - windows_server_2016
  - windows_server_2016 = 20h2
  - windows_server_2016 = 2004
  - windows_server_2019
published: '2021-07-14'
updated: '2026-08-10'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2021-33745'
references:
  - url: 'https://msrc.microsoft.com/update-guide/vulnerability/CVE-2021-33745'
    label: secure@microsoft.com
  - url: >-
      https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-33745
    label: af854a3a-2127-422b-91ae-364da2661108
tags:
  - nvd
epss: 0.02845
epssPercentile: 0.86087
ingestedAt: '2026-08-10T16:41:14.701Z'
---

## Overview

Windows DNS Server Denial of Service Vulnerability

## Affected

- `windows_server_2008`
- `windows_server_2008 = r2`
- `windows_server_2012`
- `windows_server_2012 = r2`
- `windows_server_2016`
- `windows_server_2016 = 20h2`
- `windows_server_2016 = 2004`
- `windows_server_2019`

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.