Windows SmartScreen: Use after free allows local privilege escalation
Summary
Windows SmartScreen, the reputation-based filter that checks downloaded files, apps and web content, contains a use-after-free flaw (CWE-416). An authorized local user can exploit it to elevate privileges on the affected system. Exploitation requires local access and, according to press reports, winning a race condition. Reports describe the impact as an increase from low to medium integrity level; this is not confirmed by the vendor in the sources reviewed.
Affected
- Windows 11 version 23H2: 10.0.22631.0 to before 10.0.22631.7652
- Windows 11 version 24H2: 10.0.26100.0 to before 10.0.26100.9711
- Windows 11 version 25H2: 10.0.26200.0 to before 10.0.26200.9711
- Windows 11 version 26H1: 10.0.28000.0 to before 10.0.28000.3231
- Windows 11 version 26H2: 10.0.26300.0 to before 10.0.26300.9711
- Windows Server 2025 (including Server Core): 10.0.26100.0 to before 10.0.26100.33650
Fixed in
- Windows 11 version 23H2: 10.0.22631.7652 or later
- Windows 11 version 24H2: 10.0.26100.9711 or later
- Windows 11 version 25H2: 10.0.26200.9711 or later
- Windows 11 version 26H1: 10.0.28000.3231 or later
- Windows 11 version 26H2: 10.0.26300.9711 or later
- Windows Server 2025: 10.0.26100.33650 or later
KB numbers from secondary sources, to be verified against the MSRC advisory: KB5126653 (Windows 11 23H2), KB5126646 (Windows Server 2025).
Workaround
No vendor-documented workaround known. Installing the security update is the remedy.
Exploitation
- No known exploitation in the wild; not listed in the CISA KEV catalogue (per OpenCVE; direct KEV check not performed).
- CISA SSVC: exploitation none, automatable no, technical impact total.
- No public proof-of-concept found in the searches performed; this does not prove that none exists.
Our recommendation
- Install the October 2026 cumulative update on all affected Windows 11 and Windows Server 2025 systems, with priority on multi-user systems, Remote Desktop/terminal servers and shared workstations.
- Update the asset inventory: the CPE data lists only Windows 11 23H2, but the advisory covers further versions and Windows Server 2025.
- Check whether Windows 11 23H2 Enterprise or Education is still serviced, as Microsoft's lifecycle dates should be verified; plan an upgrade if necessary.
- Monitor for unusual privilege changes on endpoints.
Information from Microsoft (Patch Tuesday October 2026)
Public exploits
PoC-in-GitHub, Metasploit and Exploit-DB list nothing for this CVE.
Research sources
- Microsoft Security Update Guide: CVE-2026-85851 msrc.microsoft.com
- NVD record via Vulners vulners.com
- VulnRichment via Vulners vulners.com
- Microsoft MS-CVE entry via Vulners vulners.com
- OpenCVE entry app.opencve.io
- VulDB entry vuldb.com
- Cybersecurity News article on the vulnerability cybersecuritynews.com
- Microsoft 2026 CVEs customer risk document cdn-dynmedia-1.microsoft.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, 01:58.
Original description (NVD)
Use after free 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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