Microsoft Windows Core Messaging: Elevation of privilege via untrusted pointer dereference
Summary
An untrusted pointer dereference in the Windows Core Messaging component allows an authorized local attacker to elevate privileges. The attacker needs a valid low-privileged account and local code execution on the affected system. The flaw cannot be exploited remotely; CVSS 3.1 base score is 7.8 (High).
Affected
- Windows 10 Version 1607 (builds 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 2016 (incl. Server Core, builds below 10.0.14393.9612)
- Windows Server 2019 (incl. Server Core, builds below 10.0.17763.9376)
- Windows Server 2022 (builds below 10.0.20348.5761)
Fixed in
- Windows 10 Version 1607 / Server 2016: 10.0.14393.9612 (KB5126868, to be confirmed on MSRC)
- Windows 10 Version 1809 / Server 2019: 10.0.17763.9376
- Windows 10 Version 21H2: 10.0.19044.7807
- Windows 10 Version 22H2: 10.0.19045.7807
- Windows 11 Version 23H2: 10.0.22631.7652
- Windows 11 Version 24H2 / 25H2 / 26H2: 10.0.26100.9711 / 10.0.26200.9711 / 10.0.26300.9711
- Windows 11 Version 26H1: 10.0.28000.3231
- Windows Server 2022: 10.0.20348.5761
The fix is delivered through the Microsoft security updates of October 2026.
Workaround
Unknown. No workaround is documented; patching is the only documented remediation.
Exploitation
- Not listed in CISA KEV.
- CISA SSVC: exploitation none, not automatable, total technical impact.
- EPSS is very low (about 0.0035).
- No public proof of concept or exploitation reports found.
Our recommendation
- Inventory all Windows 10 1607 and Server 2016 hosts, and check for other outdated Windows builds.
- Install the October 2026 security update for each affected version; for 1607 this is KB5126868 (confirm on the MSRC page).
- Prioritise multi-user systems, terminal servers and hosts that can run untrusted code.
- Plan an upgrade for systems that can no longer receive security updates; check Microsoft's lifecycle page for 1607 first.
Information from Microsoft (Patch Tuesday October 2026)
- Severity (Microsoft)
- Important
- Impact
- Elevation of privilege – Windows Core Messaging
- 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, KB5126657, KB5126646, KB5127648, KB5126653
Public exploits
PoC-in-GitHub, Metasploit and Exploit-DB list nothing for this CVE.
Research sources
- MSRC Security Update Guide: CVE-2026-83587 msrc.microsoft.com
- OpenCVE: CVE-2026-83587 app.opencve.io
- Vulners CVE list: CVE-2026-83587 vulners.com
- Tenable Nessus plugin 365471 (KB5126868) www.tenable.com
- CWE-822 description exploit-intel.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 2 Nov 2026, 03:32.
Original description (NVD)
Untrusted pointer dereference in Windows Core Messaging allows an authorized attacker to elevate privileges locally.
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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