Microsoft Windows DNS Server: Remote code execution via type confusion
Summary
A type confusion weakness (CWE-843) in the Windows Domain Name Service (DNS Server role) allows an unauthorized attacker to execute code over the network. The CVSS 8.8 vector also includes user interaction (UI:R), which Microsoft should clarify, since a DNS server bug normally needs none. The CNA record lists Windows 10, Windows 11, Windows Server 2012 to 2016 and several builds, while the CPE data lists Windows 10 1607.
Affected
- Windows 10 Version 1607 (10.0.14393.0 to < 10.0.14393.9612)
- Windows 10 Version 1809 (10.0.17763.0 to < 10.0.17763.9376)
- Windows 10 Version 21H2 and 22H2 (10.0.19044.0 to < 10.0.19044.7807; 10.0.19045.0 to < 10.0.19045.7807)
- Windows 11 Version 23H2, 24H2, 25H2, 26H1 and 26H2 (see the MSRC page for exact builds)
- Windows Server 2012 and 2012 R2, including Server Core (6.2.9200.0 to < 6.2.9200.26434; 6.3.9600.0 to < 6.3.9600.23470)
- Windows Server 2016 (10.0.14393.0 to < 10.0.14393.9612)
Fixed in
- Windows 10 1607 and Windows Server 2016: build 10.0.14393.9612 or later
- Windows 10 1809: build 10.0.17763.9376 or later
- Windows 10 21H2 and 22H2: build 10.0.19044.7807 or 10.0.19045.7807 or later
- Windows Server 2012 and 2012 R2: build 6.2.9200.26434 or 6.3.9600.23470 or later
- KB number: Unknown. Check the MSRC update guide.
Workaround
Unknown. No official workaround or mitigation was found.
Exploitation
- No public exploit code is known; MSRC rates exploit maturity as Unproven.
- No evidence of active exploitation in the wild.
- CISA SSVC: Exploitation none, Automatable no, Technical Impact total.
- EPSS around 0.8 to 0.9 percent (third-party data).
Our recommendation
- Inventory all DNS servers and identify any running Windows 10 1607 or Windows Server 2012 and 2016.
- Apply the fixed builds from Microsoft's update guide as soon as possible.
- Windows 10 Enterprise LTSB 2016 (1607) reaches end of support on 13 October 2026; plan migration or Extended Security Updates.
- Restrict access to DNS server ports from untrusted networks and keep DNS servers off internet-facing segments.
- Monitor DNS servers for crashes or unusual activity.
Information from Microsoft (Patch Tuesday October 2026)
- Severity (Microsoft)
- Important
- Impact
- Remote code execution – Role: DNS Server
- Status on Patch Tuesday
- Neither exploited nor publicly disclosed
- Exploitability assessment
- Exploitation unlikely
- Product family
- Windows, Windows ESU (Extended Security Updates)
- Updates (KB)
- KB5126651, KB5126655, KB5126657, KB5126646, KB5127648, KB5126653
Public exploits
PoC-in-GitHub, Metasploit and Exploit-DB list nothing for this CVE.
Research sources
- MSRC Security Update Guide: CVE-2026-83642 msrc.microsoft.com
- NVD aggregated data (Vulners) vulners.com
- OpenCVE (CISA SSVC data) app.opencve.io
- Vicarius: Microsoft October 2026 Patch Tuesday www.vicarius.io
- 4sysops: Windows 10 Enterprise LTSB 2016 end of support 4sysops.com
Researched and written up in English and German by an AI (Claude by Anthropic) based on NVD, CISA, EPSS and the sources listed. The vendor information is authoritative. Researched on 31 Oct 2026, 18:37.
Original description (NVD)
Access of resource using incompatible type ('type confusion') in DNS Server allows an unauthorized attacker to execute code over a network.
NVD references (1)
Sources
The tracker combines official, freely usable data sources – updated continuously:
- NVD (NIST) – CVEs, rating (CVSS), affected products
- CISA KEV – vulnerabilities confirmed by CISA as actively exploited
- CISA Vulnrichment – CISA assessment (SSVC) in the official CVE record
- FIRST EPSS – probability of exploitation
- Microsoft MSRC – Patch Tuesday: vulnerabilities, severity, updates
- PoC-in-GitHub – public proof-of-concept repositories
- Metasploit (Rapid7) – modules of the Metasploit Framework
- Exploit-DB (OffSec) – archive of public exploits (links only)
- Patch days: official vendor pages (linked per vendor) (Vendor patch days)
This product uses data from the NVD API but is not endorsed or certified by the NVD. EPSS data © FIRST.org.
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