Windows Active Directory Domain Services: Remote code execution
Summary
Microsoft has fixed an out-of-bounds write in Windows Active Directory Domain Services (AD DS), the directory service on Windows Server and domain controllers. An authorized attacker with valid low-privilege domain credentials can execute code over the network, and the CVSS rating assumes total loss of confidentiality, integrity and availability. Exposure is mainly internal, because no internet access is required, but compromising a domain controller would give an attacker control of the whole domain.
Affected
- Windows 10 Version 1607 (10.0.14393.0 before 10.0.14393.9612)
- Windows 10 Version 1809 (10.0.17763.0 before 10.0.17763.9376)
- Windows 10 Version 21H2 (10.0.19044.0 before 10.0.19044.7807)
- Windows 10 Version 22H2 (10.0.19045.0 before 10.0.19045.7807)
- Windows 11 Version 23H2 (10.0.22631.0 before 10.0.22631.7652)
- Windows 11 Version 24H2 (10.0.26100.0 before 10.0.26100.9711)
- Windows 11 Version 25H2 (10.0.26200.0 before 10.0.26200.9711)
- Windows 11 Version 26H1 (10.0.28000.0 before 10.0.28000.3231)
- Windows 11 Version 26H2 (10.0.26300.0 before 10.0.26300.9711)
- Windows Server 2012 and Server Core (6.2.9200.0 before 6.2.9200.26434)
- Windows Server 2012 R2 and Server Core (6.3.9600.0 before 6.3.9600.23470)
- Windows Server 2016 (10.0.14393.0 before 10.0.14393.9612)
Fixed in
- Apply the October 2026 security update for your exact build (MSRC entry for CVE-2026-88165).
- Windows 10 Version 1607 and Windows Server 2016: build 10.0.14393.9612 or later. The KB number is unknown.
- Other builds: first fixed builds as listed under affected products.
Workaround
Unknown.
Exploitation
- No evidence of exploitation in the wild found.
- CISA SSVC assessment: exploitation none, not automatable.
- Microsoft exploit maturity: Unproven. No public exploit known.
- EPSS: about 0.85%.
Our recommendation
- Inventory all domain controllers and AD DS hosts with exact build numbers.
- Patch each host using the MSRC entry for its build. If Windows 10 1607 or Server 2016 is out of support, plan an upgrade and isolate the host until then.
- Restrict AD DS management and network access to trusted subnets, and block exposure of LDAP, Kerberos and RPC to untrusted networks.
- Monitor for a CISA KEV listing or public proof-of-concept code, and review domain account usage.
Information from Microsoft (Patch Tuesday October 2026)
- Severity (Microsoft)
- Important
- Impact
- Remote code execution – Active Directory Domain Services
- Status on Patch Tuesday
- Neither exploited nor publicly disclosed
- Exploitability assessment
- Exploitation less likely
- Product family
- Windows, Windows ESU (Extended Security Updates)
- Updates (KB)
- KB5127648, KB5126651, KB5126655, KB5126657, KB5126646, KB5126653
Public exploits
PoC-in-GitHub, Metasploit and Exploit-DB list nothing for this CVE.
Research sources
- Microsoft Security Response Center: CVE-2026-88165 msrc.microsoft.com
- CVE record (CNA JSON, Vulners) vulners.com
- OpenCVE: CVE-2026-88165 app.opencve.io
- Strix: CVE-2026-88165 www.strix.ai
- VulDB: CVE-2026-88165 vuldb.com
- Vulners: Microsoft KB entries (Tenable) vulners.com
- Vulners: VulnCheck/VulnRichment data (EPSS) vulners.com
- GitHub alert (third-party, not authoritative) github.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, 18:03.
Original description (NVD)
Out-of-bounds write in Active Directory Domain Services 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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