Windows Event Tracing: Use after free leads to local privilege escalation
Summary
A use-after-free vulnerability (CWE-416) in Windows Event Tracing (ETW) allows an authorized local attacker to elevate privileges. The CVSS 3.1 base score is 7.0 (HIGH), with high attack complexity, low privileges required and no user interaction. Exploitation requires a local, low-privileged account, so the flaw is not directly internet-facing, but it is relevant where attackers already have a foothold.
Affected
- Windows 10 Version 1607 (builds below 10.0.14393.9612)
- Windows 10 Version 1809 (builds below 10.0.17763.9376)
- Windows 10 Version 21H2 (builds below 10.0.19044.7807)
- Windows 10 Version 22H2 (builds below 10.0.19045.7807)
- Windows 11 Version 23H2 (builds below 10.0.22631.7652)
- Windows 11 Version 24H2 (builds below 10.0.26100.9711)
- Windows 11 Version 25H2 (builds below 10.0.26200.9711)
- Windows 11 Version 26H1 (builds below 10.0.28000.3231)
- Windows 11 Version 26H2 (builds below 10.0.26300.9711)
- Windows Server 2016, including Server Core (builds below 10.0.14393.9612)
- Windows Server 2019, including Server Core (builds below 10.0.17763.9376)
- Windows Server 2022 (builds below 10.0.20348.5761)
Fixed in
- Fixed builds according to the CNA record: 10.0.14393.9612 (1607 and Server 2016), 10.0.17763.9376 (1809 and Server 2019), 10.0.19044.7807 (21H2), 10.0.19045.7807 (22H2), 10.0.22631.7652 (23H2), 10.0.26100.9711 (24H2), 10.0.26200.9711 (25H2), 10.0.28000.3231 (26H1), 10.0.26300.9711 (26H2), 10.0.20348.5761 (Server 2022)
- KB5126868 (build 14393.9612) is listed for Windows 10 1607 but its explicit link to this CVE is unconfirmed.
- Verify the fixed-build table against the MSRC advisory before rollout.
Workaround
Unknown. No workaround was found; patching is the remedy.
Exploitation
- Not listed in CISA KEV.
- CISA SSVC: exploitation none, automatable no, technical impact total.
- EPSS below 1 percent.
- No public proof of concept found.
Our recommendation
- Patch Windows 10 1607 and Server 2016 hosts to build 14393.9612 or later, and apply the October 2026 updates to all other listed systems.
- Check the MSRC known-issues notes for KB5126868 before rollout.
- Prioritise shared or multi-user endpoints and servers where local users or service accounts exist.
- Check whether Windows 10 1607 and Server 2016 are still within Microsoft support; plan an upgrade if not.
- Monitor for unusual privilege changes on endpoints.
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, 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-2026-83707 msrc.microsoft.com
- Microsoft October 2026 release notes msrc.microsoft.com
- Microsoft KB5126868 for Windows 10 1607 support.microsoft.com
- OpenCVE: CVE-2026-83707 app.opencve.io
- Vulners: CVE-2026-83707 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, 08:31.
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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