Microsoft Windows: Elevation of privilege in Windows Event Tracing (CVE-2026-70134)
Summary
A use-after-free flaw in the Windows Event Tracing component allows a local, authorized attacker to elevate privileges on affected Windows systems. Exploitation requires high complexity conditions and an existing low-privilege account on the machine, so the attacker must already have a foothold. Microsoft has released fixes, and the CVSS base score is 7.0 (High).
Affected
- Windows 10 Version 1809 and Windows Server 2019 (including Server Core): 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 and 25H2, Windows Server 2025 (including Server Core): builds before 10.0.26100.9711 (Server 2025: 10.0.26100.33650)
- Windows 11 Version 26H1: builds before 10.0.28000.3231
- Windows 11 Version 26H2: builds before 10.0.26300.9711
- Windows Server 2022: builds before 10.0.20348.5761
Fixed in
- Windows 10 1809 / Server 2019: OS Build 17763.9376 (KB5126651)
- Windows 10 21H2 / 22H2: builds 19044.7807 and 19045.7807 (KB5126657)
- Windows Server 2022: build 20348.5761 (KB5126655)
- Other versions: see the Microsoft Security Update Guide for the matching build
Workaround
Unknown. No vendor-documented mitigation is known; install the security update.
Exploitation
- Not listed in CISA's KEV catalogue
- CISA SSVC: exploitation none, automatable no, technical impact total
- EPSS below 1 percent
- No public proof-of-concept found in the research; this has not been exhaustively verified
Our recommendation
- Install the Microsoft security update for your Windows version from the October 2026 cumulative update cycle
- Verify that no machine runs Windows 10 1809 Home or Pro, which are out of support and will not receive this fix
- Prioritise shared PCs, terminal servers and multi-user systems
- Review local administrator and low-privilege accounts and restrict local logon where possible
- Check the NVD status and MSRC advisory before finalising your assessment
Information from Microsoft (Patch Tuesday October 2026)
- Severity (Microsoft)
- Important
- Impact
- Elevation of privilege – Windows Event Tracing
- 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, KB5126655, KB5126653, KB5127648, KB5126646
Public exploits
PoC-in-GitHub, Metasploit and Exploit-DB list nothing for this CVE.
Research sources
- Microsoft Security Update Guide: CVE-2026-70134 msrc.microsoft.com
- OpenCVE: CVE-2026-70134 app.opencve.io
- Vulners CVElist: CVE-2026-70134 vulners.com
- Vulners Rapid7: Microsoft Windows CVE-2026-70134 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, 09:13.
Original description (NVD)
Use after free in Windows Event Tracing 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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