Windows DNS Server: Heap-based buffer overflow leading to remote code execution
Summary
A heap-based buffer overflow in the Windows Domain Name Service (DNS Server role) allows an authorized network attacker to execute code. The attacker needs valid low-privilege access to the network and the DNS service, and the CVSS base score is 8.8 (High). If the DNS role runs on a domain controller, code execution there could also affect authentication and directory services.
Affected
- Windows Server 2016 and Windows Server 2016 (Server Core): builds 10.0.14393.0 to below 10.0.14393.9688
- Windows Server 2019 and Windows Server 2019 (Server Core): builds 10.0.17763.0 to below 10.0.17763.9487
- Windows Server 2022: builds 10.0.20348.0 to below 10.0.20348.5870
- Windows Server 2025 and Windows Server 2025 (Server Core): builds 10.0.26100.0 to below 10.0.26100.33822
Fixed in
- Fixed builds according to the CVE record: 10.0.14393.9688, 10.0.17763.9487, 10.0.20348.5870 and 10.0.26100.33822 or later
- Specific KB number: Unknown. Check the Microsoft Security Update Guide.
Workaround
Unknown. No vendor workaround is documented.
Exploitation
Unknown. No reports of exploitation in the wild, no public proof of concept and no CISA KEV entry were found at the time of research.
Our recommendation
- Identify all Windows Server systems with the DNS role, especially domain controllers and any internet-facing DNS servers.
- Check the Microsoft Security Update Guide for the fixed KB and install the security update on affected systems.
- Restrict access to the DNS service and disable unneeded recursion until patched.
- Monitor CISA KEV and vendor channels for news on exploitation.
Information from Microsoft (Patch Tuesday November 2026)
- Severity (Microsoft)
- Important
- Impact
- Remote code execution – Role: DNS Server
- Status on Patch Tuesday
- Neither exploited nor publicly disclosed
- Exploitability assessment
- Exploitation less likely
- Product family
- Windows, Windows ESU (Extended Security Updates)
- Updates (KB)
- KB5131291, KB5131085, KB5131090, KB5131080, KB5131077
Public exploits
PoC-in-GitHub, Metasploit and Exploit-DB list nothing for this CVE.
Research sources
- Microsoft Security Update Guide: CVE-2026-96064 msrc.microsoft.com
- Microsoft November 2026 Patch Tuesday (CyberSecurityNews) cybersecuritynews.com
- Windows DNS Server RCE flaw: DNS role context (WindowsForum) windowsforum.com
- CWE-122 heap-based buffer overflow (Enginsight) cve.enginsight.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 10 Nov 2026, 20:52.
Original description (NVD)
Heap-based buffer overflow in DNS Server allows an authorized 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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