Microsoft Windows: Remote code execution in RPC Runtime

Summary

A type confusion flaw in the Windows RPC Runtime component affects multiple Windows client and server editions, including Windows 10 1607. An unauthenticated remote attacker can execute code over the network if a user interacts with a crafted request or resource. The CVSS base score is 8.8 (High). Microsoft's CNA record gives no exploitation status beyond the CISA SSVC assessment (exploitation: none, automatable: no, technical impact: total).

Affected

• Windows 10 Version 1607 (builds 10.0.14393.0 to below 10.0.14393.9612)
• Windows 10 Version 1809 (builds below 10.0.17763.9376)
• Windows 10 Version 21H2 (builds below 10.0.19044.7807)
• Windows 10 Version 22H2 (builds below 10.0.19045.7807)
• Windows 11 Version 23H2 (builds below 10.0.22631.7652)
• Windows 11 Version 24H2 (builds below 10.0.26100.9711)
• Windows 11 Version 25H2 (builds below 10.0.26200.9711)
• Windows 11 Version 26H1 (builds below 10.0.28000.3231)
• Windows 11 Version 26H2 (builds below 10.0.26300.9711)
• Windows Server 2012 and Server Core installation (builds below 6.2.9200.26434)
• Windows Server 2012 R2 and Server Core installation (builds below 6.3.9600.23470)
• Windows Server 2016 (builds below 10.0.14393.9612)

Note: the CPE in the source data lists only Windows 10 1607; the CNA record lists the products above.

Fixed in

• Install the October 2026 security updates from Microsoft (the fixed builds are listed in the affected section).
• Windows 10 1607 / Server 2016: build 10.0.14393.9612 or later.
• Windows 10 1607 KB number: Unknown.
• Verify the fixed builds and KB numbers on the Microsoft Security Update Guide before deployment.

Workaround

• No official Microsoft workaround confirmed.
• Generic mitigation (not Microsoft guidance): block RPC traffic from untrusted networks at firewalls and review firewall rules for RPC.

Exploitation

• No evidence of exploitation in the wild found; not listed in CISA KEV at the time of research.
• No public proof-of-concept found for this CVE.
• A Tenable plugin for the October update references this CVE with an exploit flag, but this flag applies to the update as a whole and does not confirm a PoC.
• CISA SSVC: exploitation none, not automatable.

Our recommendation

• Inventory all Windows systems and identify affected builds, including any Windows 10 1607 hosts.
• Patch affected systems first where RPC is reachable from untrusted networks, then apply the October 2026 updates in the normal cycle.
• Block RPC access from the internet and untrusted network segments.
• Monitor logs for unusual RPC traffic.
• Check the Microsoft lifecycle for Windows 10 1607; if no fix is available, plan an upgrade.

Public exploits iAttack code is publicly available (PoC on GitHub, Metasploit or Exploit-DB).

PoC-in-GitHub, Metasploit and Exploit-DB list nothing for this CVE.

Research sources

• Microsoft Security Update Guide: CVE-2026-102203 msrc.microsoft.com
• NVD record via vulners.com vulners.com
• EUVD mirror via vulners.com vulners.com
• Strix.ai CVE overview www.strix.ai
• Zero Day Observer: RPC Runtime type confusion flaw zerodayobserver.com
• Shell Bulletin: Verify Windows RPC patches shellbulletin.com
• Tenable plugin 365470 www.tenable.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, 19:35.