Microsoft Windows Hello: Elevation of privilege via use after free
Summary
Windows Hello, the biometric and PIN sign-in component of Windows, contains a use-after-free weakness (CWE-416) that allows a local attacker with low privileges to elevate their rights. Microsoft lists the issue with maximum severity Important and a CVSS 3.1 base score of 7.0. Exploitation requires local access and a low-privilege account, and the attack is considered hard to carry out.
Affected
- Windows 10 Version 1809: below 10.0.17763.9376 (CPE data lists only this version)
- Windows 10 Version 21H2: below 10.0.19044.7807
- Windows 10 Version 22H2: below 10.0.19045.7807
- Windows 11 Version 23H2: below 10.0.22631.7652
- Windows 11 Version 24H2: below 10.0.26100.9711
- Windows 11 Version 25H2: below 10.0.26200.9711
- Windows 11 Version 26H1: below 10.0.28000.3231
- Windows 11 Version 26H2: below 10.0.26300.9711
- Windows Server 2019 (including Server Core): below 10.0.17763.9376
- Windows Server 2022: below 10.0.20348.5761
- Windows Server 2025 (including Server Core): below 10.0.26100.33650
Fixed in
- Microsoft security updates of October 13, 2026 (the fixed builds are the versions listed above)
- Named update titles per Tenable (not verified): KB5126651 for Windows 10 1809 and Server 2019, KB5126646 for Windows Server 2025, KB5126653 for Windows 11 23H2
Workaround
Unknown. No workaround is documented; patching is the only confirmed fix.
Exploitation
- No evidence of exploitation in the wild found.
- CISA SSVC: Exploitation none, automatable no.
- Exploit code maturity is marked unproven (E:U).
- No public proof of concept found; this does not prove none exists.
- EPSS about 0.25 to 0.29 percent in aggregator snapshots.
Our recommendation
- Install the October 2026 cumulative updates on all affected Windows 10, Windows 11 and Windows Server systems.
- Prioritise shared workstations, systems with weak local account hygiene and systems with many users.
- Confirm the Windows edition and build on each device; Windows 10 1809 general-purpose editions are out of support, so remaining 1809 systems are likely LTSC builds.
- Reduce the risk of initial footholds through phishing protection and restricted local accounts.
- Verify the exact fixed builds in the MSRC advisory before planning the update.
Information from Microsoft (Patch Tuesday October 2026)
- Severity (Microsoft)
- Important
- Impact
- Elevation of privilege – Windows Hello
- 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 Update Guide: CVE-2026-83740 msrc.microsoft.com
- Vulners CNA record (CVELIST) vulners.com
- Vulners MSCVE record vulners.com
- OpenCVE CVE-2026-83740 app.opencve.io
- Vulners NVD record (EPSS data) vulners.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 4 Nov 2026, 08:24.
Original description (NVD)
Use after free in Windows Hello 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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