Windows Media Foundation: Heap buffer overflow allows local privilege escalation
Summary
A heap-based buffer overflow in Microsoft Windows Media Foundation affects multiple supported and older Windows 10, Windows 11 and Windows Server versions. An attacker with a low-privilege account or code already running on the system can exploit it locally to gain higher privileges, with a changed scope that can reach beyond the vulnerable component. Exploitation requires high attack complexity, and no exploitation in the wild is known.
Affected
- Windows 10 Version 1607 (10.0.14393.0 to before 10.0.14393.9612)
- Windows 10 Version 1809 (10.0.17763.0 to before 10.0.17763.9376)
- Windows 10 Version 21H2 (10.0.19044.0 to before 10.0.19044.7807)
- Windows 10 Version 22H2 (10.0.19045.0 to before 10.0.19045.7807)
- Windows 11 Version 23H2 (10.0.22631.0 to before 10.0.22631.7652)
- 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)
- Windows Server 2012 incl. Server Core (6.2.9200.0 to before 6.2.9200.26434)
- Windows Server 2012 R2 incl. Server Core (6.3.9600.0 to before 6.3.9600.23470)
- Windows Server 2016 (10.0.14393.0 to before 10.0.14393.9612)
Fixed in
- Windows 10 Version 1607: 10.0.14393.9612 (update released October 13, 2026; KB number unknown)
- Windows 10 Version 1809: 10.0.17763.9376
- Windows 10 Version 21H2 and 22H2: 10.0.19044.7807 / 10.0.19045.7807
- Windows 11 Version 23H2: 10.0.22631.7652
- Windows 11 Version 24H2, 25H2 and 26H2: 10.0.26100.9711 / 10.0.26200.9711 / 10.0.26300.9711
- Windows 11 Version 26H1: 10.0.28000.3231
- Windows Server 2012: 6.2.9200.26434
- Windows Server 2012 R2: 6.3.9600.23470
- Windows Server 2016: 10.0.14393.9612
Workaround
Unknown. No vendor workaround was identified; install the security update.
Exploitation
- Not known to be exploited in the wild; not listed in the CISA KEV catalog.
- CISA SSVC: exploitation none, automatable no, technical impact total.
- No public proof-of-concept found in research; this does not prove absence.
- EPSS scores reported as low.
Our recommendation
- Install the October 2026 Microsoft security update on all affected systems, prioritising Windows 10 1607, Windows Server 2016 and other multi-user or older systems.
- Check whether any affected system is out of Microsoft support; such systems will not receive a fix and should be upgraded.
- Verify the installed build number after patching.
- Restrict local logons and limit accounts on terminal servers, Remote Desktop hosts and shared PCs.
Information from Microsoft (Patch Tuesday October 2026)
- Severity (Microsoft)
- Important
- Impact
- Elevation of privilege – Microsoft Windows Media Foundation
- 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-2026-70278 msrc.microsoft.com
- Microsoft Security Update Guide (en-US) msrc.microsoft.com
- NVD via Vulners vulners.com
- CVE record (CNA data) via Vulners vulners.com
- OpenCVE app.opencve.io
- Microsoft advisory mirror via Vulners 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 2 Nov 2026, 03:52.
Original description (NVD)
Heap-based buffer overflow in Microsoft Windows Media Foundation 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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