Windows SmartScreen: Local privilege escalation via type confusion
Summary
Windows SmartScreen, the reputation and phishing filter built into Windows, contains a type confusion flaw (CWE-843). An authorized local user with low privileges can exploit it to elevate privileges on the system. An attacker therefore needs an existing low-privileged account on the affected machine, for example after a phishing or malware infection. No user interaction is required. The CVSS base score is 7.8 (High).
Affected
- Windows 10 Version 1809 (before 10.0.17763.9376)
- Windows 10 Version 21H2 (before 10.0.19044.7807)
- Windows 10 Version 22H2 (before 10.0.19045.7807)
- Windows 11 Version 23H2 (before 10.0.22631.7652)
- Windows 11 Version 24H2 (before 10.0.26100.9711)
- Windows 11 Version 25H2 (before 10.0.26200.9711)
- Windows 11 Version 26H1 (before 10.0.28000.3231)
- Windows 11 Version 26H2 (before 10.0.26300.9711)
- Windows Server 2019, including Server Core (before 10.0.17763.9376)
- Windows Server 2022 (before 10.0.20348.5761)
- Windows Server 2025, including Server Core (before 10.0.26100.33650)
Fixed in
- Security updates released by Microsoft on October 13, 2026, for the affected Windows versions listed above. Build numbers are from the CNA record and must be verified against the MSRC KB articles before rollout.
Workaround
Unknown.
Exploitation
- Microsoft rates exploit maturity as Unproven and states that no publicly available exploit code exists.
- CISA SSVC assessment: exploitation none, not automatable, total technical impact.
- EPSS score: 0.00341.
- No reports of exploitation in the wild or CISA KEV entry were found in the research. Searches were limited.
Our recommendation
- Install the October 13, 2026 security updates on all affected Windows 10, 11 and Server systems, starting with shared workstations, terminal servers and systems where users open untrusted files.
- Verify the build numbers and KB articles in the MSRC Security Update Guide before rollout.
- Identify Windows 10 1809 and 21H2 systems that are out of support or lack ESU coverage and plan upgrades.
- Restrict local logons and untrusted file execution on shared systems.
- Monitor endpoints for unexpected privilege changes and suspicious processes.
Information from Microsoft (Patch Tuesday October 2026)
- Severity (Microsoft)
- Important
- Impact
- Elevation of privilege – Windows SmartScreen
- 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
- Microsoft Security Update Guide: CVE-2026-70051 msrc.microsoft.com
- Vulners: NVD record CVE-2026-70051 vulners.com
- Vulners: CVE List record CVE-2026-70051 vulners.com
- Strix: CVE-2026-70051 www.strix.ai
- CybersecurityNews: Windows SmartScreen escalation vulnerability cybersecuritynews.com
- OpenCVE: CVE-2026-70051 app.opencve.io
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, 04:28.
Original description (NVD)
Access of resource using incompatible type ('type confusion') in Windows SmartScreen 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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