Microsoft Windows Media Foundation: Deserialization leads to local privilege escalation
Summary
Deserialization of untrusted data in Microsoft Windows Media Foundation allows a locally authorized attacker to elevate privileges. Exploitation requires local access and low privileges, with no user interaction. Successful exploitation would give the attacker a high impact on confidentiality, integrity and availability of the affected system.
Affected
- Windows 10 Version 1607 (below 10.0.14393.9612)
- Windows 10 Version 1809 (below 10.0.17763.9376)
- Windows 10 Version 21H2 (below 10.0.19044.7807)
- Windows 10 Version 22H2 (below 10.0.19045.7807)
- Windows 11 Version 23H2 (below 10.0.22631.7652)
- Windows 11 Version 24H2 (below 10.0.26100.9711)
- Windows 11 Version 25H2 (below 10.0.26200.9711)
- Windows 11 Version 26H1 (below 10.0.28000.3231)
- Windows 11 Version 26H2 (below 10.0.26300.9711)
- Windows Server 2012 (below 6.2.9200.26434)
- Windows Server 2012 R2 (below 6.3.9600.23470)
- Windows Server 2016 (below 10.0.14393.9612)
Fixed in
- Fixed in the Microsoft security update of October 13, 2026 (Patch Tuesday).
- Fixed builds: see the affected builds above (the first build listed as not affected).
- Unknown: the exact KB number for Windows 10 1607 and Windows Server 2016.
Workaround
Unknown. Microsoft documents no interim workaround in the sources reviewed.
Exploitation
- No known exploitation at the time of research.
- CISA SSVC: exploitation none, not automatable, total technical impact.
- Not confirmed: whether public proof-of-concept code exists.
Our recommendation
- Apply the October 13, 2026 Microsoft security update to all listed systems where support is still available.
- Prioritise shared, multi-user and terminal servers (RDS) and any Windows 10 1607 or Windows Server 2016 hosts.
- Verify the support status of Windows 10 1607 and Windows Server 2016 before planning; if support has ended, plan a migration.
- Review local accounts and access rights, because an attacker needs a foothold on the system first.
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)
- KB5127648, KB5126646, KB5126835, KB5126836, KB5126868, KB5126651
Public exploits
PoC-in-GitHub, Metasploit and Exploit-DB list nothing for this CVE.
Research sources
- MSRC advisory CVE-2026-96186 msrc.microsoft.com
- CNA version data (Vulners) vulners.com
- Plain-language description (OpenCVE) app.opencve.io
- EUVD record (Vulners) vulners.com
- Same-day Windows Media Foundation EoP advisory CVE-2026-70278 (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, 01:03.
Original description (NVD)
Deserialization of untrusted data 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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