Microsoft Windows DNS Server Remote Code Execution Vulnerability

A remote code execution vulnerability exists in Windows Domain Name System servers when they fail to properly handle requests, aka 'Windows DNS Server Remote Code Execution Vulnerability'.

CheckOps priority index

9.3/10 Patch within 24 h

Severity10.0

Probability9.7

Exploitation4/5

Severity = CVSS. Probability = EPSS (FIRST). Exploitation = public signals: KEV, EUVD, ransomware, EPSS above 10 %, no account required.

EPSS · today 96.7% higher than 99.9% of CVEs

CVSS 3.1 10.0 AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:

Exploited for 1,826 days 03 Nov 2021

CISA due date 03 May 2022 for US federal agencies

Exploitation probability EPSS · FIRST

EPSS probability (%)Percentile among all CVEs

Exploitation signals 4 / 5

KEV catalog (CISA)03 Nov 2021
Exploited in EUVD (ENISA)03 Nov 2021
Used by ransomwareno
EPSS above 10 %96.7%
No account, over the networkyes

What to do

Fix

Apply the vendor’s fix as soon as it is available.

CISA guidance: Apply updates per vendor instructions.

Meanwhile

Take the service off the internet or restrict access to it, watch the logs and look for signs of compromise.

Manufacturers (CRA)

Exploited vulnerability in your product: early warning to ENISA within 24 h, then notification within 72 h (Article 14 of the Cyber Resilience Act). The CRA explained

Affected products

Windows ServerWindows Server, version 1909 (Server Core installation)Windows Server, version 2004 (Server Core installation)Windows Server, version 1903 (Server Core installation)Windows

Affected versions

2012 (Core installation)
2008 for x64-based Systems Service Pack 2
2008 for 32-bit Systems Service Pack 2 (Core installation)
2012 R2 (Core installation)
unspecified
2008 for x64-based Systems Service Pack 2 (Core installation)
2008 R2 for x64-based Systems Service Pack 1 (Core installation)
2016
2008 R2 for x64-based Systems Service Pack 1
2012 R2
2019
2016 (Core installation)

Open source packages OSV

Affected libraries according to OSV, with fixed versions.

Timeline

14 Jul 2020
Published
03 Nov 2021
Exploitation reported (ENISA)
03 Nov 2021
Added to the KEV catalog
03 May 2022
CISA remediation due date
26 Sept 2026
EPSS peak: 96.7%

References

Other exploited vulnerabilities from the same vendor

CVE-2026-96951Microsoft Windows Command Injection Vulnerability
5.6 · Actively exploited
CVE-2026-65660Microsoft SharePoint Code Injection Vulnerability
5.0 · Actively exploited
CVE-2026-85880Microsoft Windows Heap-Based Buffer Overflow Vulnerability
4.3 · Actively exploited
CVE-2026-81963Microsoft Windows Link Following Vulnerability
4.3 · Actively exploited
CVE-2019-1068Microsoft SQL Server Remote Code Execution Vulnerability
7.0 · Actively exploited
CVE-2026-69836Microsoft Entra
5.3 · Actively exploited