Windows DHCP Server: Remote code execution via race condition
Summary
A race condition in the Windows DHCP Server component allows an unauthenticated attacker to execute code over the network. The attack complexity is rated high, and no user interaction is required. Successful exploitation could affect confidentiality, integrity and availability of the DHCP server.
Affected
- Windows 10 Version 1607 (builds below 10.0.14393.9612)
- Windows 10 Version 1809 (builds below 10.0.17763.9376)
- Windows Server 2012 and 2012 Server Core (builds below 6.2.9200.26434)
- Windows Server 2012 R2 and 2012 R2 Server Core (builds below 6.3.9600.23470)
- Windows Server 2016 and Server Core (builds below 10.0.14393.9612)
- Windows Server 2019 and Server Core (builds below 10.0.17763.9376)
- Windows Server 2022 (builds below 10.0.20348.5761)
- Windows Server 2025 and Server Core (builds below 10.0.26100.33650)
Fixed in
- Install the October 2026 security update from Microsoft for the affected product.
- Fixed builds: 10.0.14393.9612 (Windows 10 1607, Server 2016), 10.0.17763.9376 (Windows 10 1809, Server 2019), 10.0.20348.5761 (Server 2022), 10.0.26100.33650 (Server 2025), 6.2.9200.26434 (Server 2012), 6.3.9600.23470 (Server 2012 R2).
Workaround
Unknown. No Microsoft workaround was found in the sources. Installing the security update is the remedy.
Exploitation
- CISA SSVC: Exploitation none, Automatable no, Technical Impact total.
- EPSS score 0.0035 (low predicted exploitation probability).
- No public proof-of-concept or in-the-wild exploitation was found.
- CISA KEV catalog status not verified.
Our recommendation
- Patch all Windows hosts running the DHCP Server role first, including Windows Server 2012 and 2012 R2.
- Check whether any Windows 10 1607 system actually runs the DHCP Server role.
- Restrict which hosts can reach the DHCP service and segment the DHCP server into a management VLAN.
- Use DHCP snooping on managed switches and monitor DHCP server logs and crashes.
- Plan a maintenance window, as patching may require a reboot and interrupt DHCP service.
Information from Microsoft (Patch Tuesday October 2026)
- Severity (Microsoft)
- Important
- Impact
- Remote code execution – Windows DHCP 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)
- KB5126651, KB5126655, KB5126646, KB5126868, KB5126835, KB5126836
Public exploits
PoC-in-GitHub, Metasploit and Exploit-DB list nothing for this CVE.
Research sources
- Microsoft Security Update Guide msrc.microsoft.com
- Zero Day Initiative October 2026 security update review www.zerodayinitiative.com
- NVD mirror (Vulners) vulners.com
- CNA/cvelist record (Vulners) vulners.com
- Rapid7 record (Vulners) vulners.com
- Tenable plugin 365468 www.tenable.com
- OpenCVE app.opencve.io
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 1 Nov 2026, 19:37.
Original description (NVD)
Concurrent execution using shared resource with improper synchronization ('race condition') in Windows DHCP 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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