---
id: CVE-2026-70091
title: >-
  Concurrent execution using shared resource with improper synchronization
  ('race condition') in Windows DNS allows an unauthorized attacker to deny
  service over a network.
summary: >-
  Concurrent execution using shared resource with improper synchronization
  ('race condition') in Windows DNS allows an unauthorized attacker to deny
  service over a network.
severity: medium
cvss: 5.9
cvssVector: 'CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H'
cwe:
  - CWE-362
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: '2026-09-24'
sourceUpdated: '2026-09-24T23:18:37.567'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-70091'
references:
  - url: 'https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-70091'
    label: secure@microsoft.com
tags:
  - nvd
  - cve.org
epss: 0.00655
epssPercentile: 0.49179
ssvc:
  exploitation: none
  automatable: 'no'
  technicalImpact: partial
  timestamp: '2026-09-08T18:17:55.362779Z'
ingestedAt: '2026-09-08T19:08:49.622Z'
---

## Overview

Concurrent execution using shared resource with improper synchronization ('race condition') in Windows DNS 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`