Microsoft MPEG-2 Video Extension: Remote code execution via heap-based buffer overflow
Summary
A heap-based buffer overflow in the Microsoft MPEG-2 Video Extension allows an attacker to execute code remotely. No privileges are required, but a user must interact with crafted content, for example by opening a malicious MPEG-1 or MPEG-2 media file. The CVSS base score is 8.8 (High), and the impact on confidentiality, integrity and availability is rated high if exploited.
Affected
- Microsoft MPEG-2 Video Extension versions 1.0.0.0 up to but excluding 1.2.32.0 (per CNA advisory)
Fixed in
- Unknown. The first fixed build has not been confirmed; check the MSRC affected-products table for the fixed version and KB article.
Workaround
- No vendor-documented workaround found.
- Avoid opening untrusted MPEG-1/MPEG-2 media files until patched.
- Restrict use of the extension where possible (general measure, not vendor guidance).
Exploitation
- Microsoft rates exploit code maturity as "Unproven".
- Not listed in CISA KEV; SSVC exploitation status is "none".
- EPSS is about 0.9%.
- No public proof of concept or in-the-wild exploitation found as of 31 Oct 2026.
Our recommendation
- Confirm the installed MPEG-2 Video Extension version on Windows endpoints.
- Apply the October 2026 Microsoft security update once the fixed build is confirmed.
- Ensure Microsoft Store app updates are not blocked.
- Prioritise unmanaged or offline machines, as they are the main risk.
- Caution users against opening untrusted media files until patched.
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-2026-70343 msrc.microsoft.com
- Qualys security alert www.qualys.com
- OpenCVE: CVE-2026-70343 app.opencve.io
- EUVD-2026-100191 vulners.com
- Strix: CVE-2026-70343 www.strix.ai
- CVE Details: Microsoft MPEG-2 Video Extension www.cvedetails.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 31 Oct 2026, 18:43.
Original description (NVD)
Heap-based buffer overflow in Microsoft MPEG-2 Video Extension allows an unauthorized attacker to execute code over a network.
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.
Affected? We can help.
We check whether your systems are affected, install updates and close the gap – continuously with the System Health Checker if you wish.