Microsoft Windows: Use-after-free in Certificates allows local privilege escalation
Summary
A use-after-free vulnerability (CWE-416) in the Windows Certificates component allows an authorized local attacker to elevate privileges. Exploitation requires an attacker who already has local access, for example through phishing, stolen credentials or another vulnerability. Microsoft's CNA record lists CVSS 3.1 7.0 (High), but third-party scores vary.
Affected
- Windows 10 Version 1607 (builds before 10.0.14393.9612)
- Windows 10 Version 1809 (builds before 10.0.17763.9376)
- Windows 10 Version 21H2 (builds before 10.0.19044.7807)
- Windows 10 Version 22H2 (builds before 10.0.19045.7807)
- Windows 11 Version 23H2 (builds before 10.0.22631.7652)
- Windows 11 Version 24H2 (builds before 10.0.26100.9711)
- Windows 11 Version 25H2 (builds before 10.0.26200.9711)
- Windows 11 Version 26H1 (builds before 10.0.28000.3231)
- Windows 11 Version 26H2 (builds before 10.0.26300.9711)
- Windows Server 2016 incl. Server Core (builds before 10.0.14393.9612)
- Windows Server 2019 incl. Server Core (builds before 10.0.17763.9376)
- Windows Server 2022 (builds before 10.0.20348.5761)
Fixed in
Install the October 2026 security updates. Fixed builds according to the Microsoft CNA record:
- Windows 10 1607 and Windows Server 2016: 10.0.14393.9612
- Windows 10 1809 and Windows Server 2019: 10.0.17763.9376
- Windows 10 21H2: 10.0.19044.7807
- Windows 10 22H2: 10.0.19045.7807
- Windows Server 2022: 10.0.20348.5761
- Windows 11 23H2: 10.0.22631.7652
- Windows 11 24H2 and 25H2: 10.0.26100.9711 and 10.0.26200.9711
- Windows 11 26H1: 10.0.28000.3231
- Windows 11 26H2: 10.0.26300.9711
Check the MSRC page for the exact update per product.
Workaround
Unknown.
Exploitation
- CISA SSVC assessment: exploitation none, not automatable, total technical impact.
- No evidence of exploitation or public proof of concept found at the time of research.
- Not listed in the CISA Known Exploited Vulnerabilities catalogue at the time of research.
Our recommendation
- Identify all Windows 10 1607, Windows Server 2016 and other affected Windows hosts.
- Install the October 2026 cumulative update or the applicable Extended Security Updates on all affected systems.
- Verify end-of-support status of Windows 10 1607 (LTSB 2016) on Microsoft's lifecycle page and plan an upgrade or ESU if support has ended.
- Prioritise systems that store sensitive data or have many local user accounts.
- Monitor for unusual privilege changes and recheck the CISA KEV catalogue.
Information from Microsoft (Patch Tuesday October 2026)
- Severity (Microsoft)
- Important
- Impact
- Elevation of privilege – Windows Certificates
- 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-2026-69840 msrc.microsoft.com
- Tenable Nessus plugin 365473 www.tenable.com
- Tenable Nessus plugin 365470 www.tenable.com
- Vulners CVELIST record CVE-2026-69840 vulners.com
- Vulners NVD record CVE-2026-69840 vulners.com
- Vulners MSCVE record MS:CVE-2026-69840 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, 09:32.
Original description (NVD)
Use after free in Windows Certificates 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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