Windows Trace Data Helper: Elevation of privilege via heap-based buffer overflow
Summary
A heap-based buffer overflow in the Microsoft Trace Data Helper component of Windows allows an authorized local user to elevate privileges. An attacker needs an existing local account and must run code on the affected system, for example through a phished user or malware running as a standard account. Successful exploitation can give full control of the system (confidentiality, integrity and availability impact rated high). The flaw is not reachable from the internet by itself.
Affected
- 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 (fixed build from a third-party source, not confirmed by the CNA record)
- Windows Server 2025 (including Server Core installation): 10.0.26100.0 to before 10.0.26100.33822 (not confirmed by the primary record)
Fixed in
- Fixed in the Microsoft security update of November 10, 2026 (Patch Tuesday).
- Fixed builds: 10.0.26100.9711 (24H2), 10.0.26200.9711 (25H2), 10.0.28000.3231 (26H1), 10.0.26300.9711 (26H2, unverified), 10.0.26100.33822 (Server 2025, unverified).
- KB numbers: Unknown.
Workaround
Unknown.
Exploitation
- Exploited in the wild: Not indicated.
- Public proof of concept: None found.
- CISA SSVC: Exploitation none, not automatable, total technical impact.
- CVSS temporal metrics: exploit code maturity Unproven.
Our recommendation
- Install the November 2026 Windows security updates on affected Windows 11 and Windows Server 2025 systems, with priority on multi-user, terminal or RDS servers.
- Check the MSRC advisory for KB numbers, exact builds and any mitigations before rollout.
- Limit local interactive logon on shared hosts and restrict who can run unsigned code.
- Monitor endpoints for privilege escalation activity with EDR or similar tools.
Information from Microsoft (Patch Tuesday November 2026)
Public exploits
PoC-in-GitHub, Metasploit and Exploit-DB list nothing for this CVE.
Research sources
- Microsoft Security Update Guide: CVE-2026-121681 msrc.microsoft.com
- CVE.org CNA record CVE-2026-121681 www.cve.org
- Strix: CVE-2026-121681 (third-party, partly unverified) www.strix.ai
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 11 Nov 2026, 03:32.
Original description (NVD)
Heap-based buffer overflow in Microsoft Trace Data Helper 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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