Microsoft Windows DNS: Double free leading to remote code execution

Summary

A double free vulnerability (CWE-415) in the Windows DNS component allows an unauthenticated attacker to execute code over the network. The CVSS v3.1 base score is 9.8 (critical), with high impact on confidentiality, integrity and availability. NVD had not yet completed its analysis when this entry was prepared, and the description is taken from the CVE record only.

Affected

• Windows 10 Version 1607: 10.0.14393.0 to before 10.0.14393.9688
• Windows 10 Version 1809: 10.0.17763.0 to before 10.0.17763.9487
• Windows 10 Version 21H2: 10.0.19044.0 to before 10.0.19044.7846
• Windows 10 Version 22H2: 10.0.19045.0 to before 10.0.19045.7846
• Windows 11 Version 23H2: 10.0.22631.0 to before 10.0.22631.7711
• Windows 11 Version 24H2: 10.0.26100.0 to before 10.0.26100.9974
• Windows 11 Version 25H2: 10.0.26200.0 to before 10.0.26200.9974
• Windows 11 Version 26H1: 10.0.28000.0 to before 10.0.28000.3501
• Windows 11 Version 26H2: 10.0.26300.0 to before 10.0.26300.9974
• Windows Server 2016 (including Server Core): 10.0.14393.0 to before 10.0.14393.9688
• Windows Server 2019 (including Server Core): 10.0.17763.0 to before 10.0.17763.9487
• Windows Server 2022: 10.0.20348.0 to before 10.0.20348.5870

Fixed in

• Fixed builds according to the CNA record (first unaffected build): 10.0.14393.9688, 10.0.17763.9487, 10.0.19044.7846, 10.0.19045.7846, 10.0.22631.7711, 10.0.26100.9974, 10.0.26200.9974, 10.0.28000.3501, 10.0.26300.9974, 10.0.20348.5870
• KB article numbers: Unknown.

Workaround

Unknown. Microsoft's mitigation guidance could not be verified.

Exploitation

• Exploited in the wild: no evidence found.
• Public proof of concept: no evidence found.
• CISA SSVC assessment: exploitation none, automatable yes, technical impact total.

Our recommendation

• Open the Microsoft Security Update Guide entry and confirm the affected products, KB numbers and exploitability flags.
• Inventory all servers running the DNS Server role, including domain controllers and any DNS server reachable from the internet.
• Prioritise patching of internet-facing DNS servers and DNS servers on domain controllers.
• Patch the remaining affected systems within the same week, and monitor NVD and the CISA Known Exploited Vulnerabilities catalogue for updates.

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-2026-88218 msrc.microsoft.com
• Related Microsoft DNS CVE (same description template, unconfirmed) vulners.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, 20:35.