Microsoft Windows: Local privilege escalation via code injection in Assigned Access
Summary
A code injection flaw (CWE-94) in the Windows Assigned Access component allows an authorized local user to elevate privileges. The attacker needs a low-privileged local account and cannot exploit the flaw remotely. CVSS 3.1 rates it 7.8 (High) with high impact on confidentiality, integrity and availability.
Affected
- Windows 10 Version 1809 and Windows Server 2019 (including Server Core): builds 10.0.17763.0 to before 10.0.17763.9376
- Windows 10 Version 21H2: builds 10.0.19044.0 to before 10.0.19044.7807
- Windows 10 Version 22H2: builds 10.0.19045.0 to before 10.0.19045.7807
- Windows 11 Version 23H2: builds 10.0.22631.0 to before 10.0.22631.7652
- Windows 11 Version 24H2: builds 10.0.26100.0 to before 10.0.26100.9711
- Windows 11 Version 25H2 and 26H2: builds 10.0.26200.0 and 10.0.26300.0 to before 10.0.26200.9711 and 10.0.26300.9711
- Windows 11 Version 26H1: builds 10.0.28000.0 to before 10.0.28000.3231
Fixed in
- Windows 10 1809 / Server 2019: KB5126651 (build 17763.9376), October 2026 cumulative update. Not yet confirmed as the fix by MSRC.
- Follow-up: KB5134124 (build 17763.9378), released October 26, 2026. Its content for this CVE is unknown.
- Other branches: install the October 2026 cumulative update for your version.
Workaround
No vendor workaround known.
Exploitation
- Not listed in CISA KEV.
- CISA SSVC: exploitation none, automatable no, technical impact total.
- No public proof of concept found and no reports of in-the-wild exploitation as of this entry.
Our recommendation
- Install the October 2026 cumulative update on all affected devices and check for the follow-up update for your branch.
- Prioritise kiosk, reception and shared devices.
- Check whether Windows 10 1809 devices are still in use, and whether they are LTSC/Server 2019 systems enrolled in Extended Security Updates.
- Until patched, limit local logon to trusted accounts and remove unneeded local accounts.
- Before patching 1809 systems with Exchange, review the Microsoft known issue for KB5126651 (email access problems on some on-premises Exchange servers).
Information from Microsoft (Patch Tuesday October 2026)
- Severity (Microsoft)
- Important
- Impact
- Elevation of privilege – Windows Assigned Access
- 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, KB5126657, KB5126653, KB5127648, KB5127646
Public exploits
PoC-in-GitHub, Metasploit and Exploit-DB list nothing for this CVE.
Research sources
- Microsoft Security Update Guide: CVE-2026-96220 msrc.microsoft.com
- OpenCVE: CVE-2026-96220 app.opencve.io
- NinjaOne KB catalog: KB5126651 www.ninjaone.com
- Microsoft release health: Windows 10 1809 and Windows Server 2019 learn.microsoft.com
- Microsoft Update Catalog: KB5126651 www.catalog.update.microsoft.com
- Wikipedia: Windows 10 en.wikipedia.org
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, 01:02.
Original description (NVD)
Improper control of generation of code ('code injection') in Windows Assigned Access 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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