Windows Direct Composition: Local privilege escalation via use-after-free
Summary
A use-after-free flaw in the Windows Direct Composition graphics component allows a local attacker with low-privilege access to elevate privileges. Exploitation requires that the attacker can already run code in the user context, for example after phishing or malware. The vulnerability is not remotely exploitable.
Affected
- Windows 11 Version 24H2: builds 10.0.26100.0 to below 10.0.26100.9711
- Windows 11 Version 25H2: builds 10.0.26200.0 to below 10.0.26200.9711
- Windows 11 Version 26H1: builds 10.0.28000.0 to below 10.0.28000.3231
- Windows 11 Version 26H2: builds 10.0.26300.0 to below 10.0.26300.9711
- Windows Server 2022: builds 10.0.20348.0 to below 10.0.20348.5761
- Windows Server 2025 (including Server Core): builds 10.0.26100.0 to below 10.0.26100.33650
Fixed in
- Windows 11 Version 24H2: build 10.0.26100.9711 or later
- Windows 11 Version 25H2: build 10.0.26200.9711 or later
- Windows 11 Version 26H1: build 10.0.28000.3231 or later
- Windows 11 Version 26H2: build 10.0.26300.9711 or later
- Windows Server 2022: build 10.0.20348.5761 or later
- Windows Server 2025: build 10.0.26100.33650 or later
Fix is included in the October 2026 Windows updates. Unknown: the cumulative update KB number for each branch.
Workaround
Unknown. No workaround or interim mitigation was found in the sources.
Exploitation
- No public proof of concept or exploit known.
- Not listed in the CISA KEV catalog.
- CISA SSVC: exploitation none, automatable no, technical impact total.
Our recommendation
- Install the October 2026 Windows security updates on affected systems, prioritising terminal servers and multi-user hosts.
- Check the MSRC advisory to confirm the build numbers before rollout.
- Keep local user privileges minimal and monitor for unusual privilege escalation.
- Re-check the CISA KEV catalog and vendor updates for changes in exploitation status.
Information from Microsoft (Patch Tuesday October 2026)
Public exploits
PoC-in-GitHub, Metasploit and Exploit-DB list nothing for this CVE.
Research sources
- Microsoft Security Update Guide: CVE-2026-70021 msrc.microsoft.com
- NVD record CVE-2026-70021 (Vulners) vulners.com
- CVE record CVE-2026-70021 (Vulners CVELIST) vulners.com
- CVE-2026-70021 exploitation and SSVC details (OpenCVE) app.opencve.io
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, 09:25.
Original description (NVD)
Use after free in Windows Direct Composition 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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