Microsoft Windows Codecs Library: Remote code execution vulnerability
Summary
A heap-based buffer overflow in the Microsoft Windows Codecs Library allows an unauthorized attacker to execute code over a network. Exploitation has high attack complexity and requires user interaction, such as opening or previewing a crafted media file. The CVSS 3.1 score is 7.5 (High), while the MSRC page lists the maximum severity as Critical, so the update should be treated as high priority.
Affected
- Windows 10 Version 1607 and Windows Server 2016 (incl. Server Core): before 10.0.14393.9688
- Windows 10 Version 1809 and Windows Server 2019 (incl. Server Core): before 10.0.17763.9487
- Windows 10 Version 21H2: before 10.0.19044.7846
- Windows 10 Version 22H2: before 10.0.19045.7846
- Windows 11 Version 23H2: before 10.0.22631.7711
- Windows 11 Version 24H2: before 10.0.26100.9974
- Windows 11 Version 25H2: before 10.0.26200.9974
- Windows 11 Version 26H1: before 10.0.28000.3501
- Windows 11 Version 26H2: before 10.0.26300.9974
- Windows Server 2022: before 10.0.20348.5870
Fixed in
Fixed in the Microsoft security update for November 2026. Builds at or above the fixed build listed in the affected section are patched. Verify the fixed builds and KB numbers on the MSRC advisory.
Workaround
Unknown.
Exploitation
- Microsoft marks exploitation as Unproven and not exploited at publication
- No public proof of concept or CISA KEV entry was found at the time of research
Our recommendation
- Install the November 2026 Microsoft security update on all affected Windows 10, 11 and Server systems, starting with Windows 10 1607, 1809 and 21H2
- Confirm each device reaches the fixed build
- Warn users not to open untrusted media files, attachments or links until patched
- Re-check the CISA KEV catalog and public proof-of-concept sources in the coming days
Information from Microsoft (Patch Tuesday November 2026)
- Severity (Microsoft)
- Critical
- Impact
- Remote code execution – Microsoft Windows Codecs Library
- Status on Patch Tuesday
- Neither exploited nor publicly disclosed
- Exploitability assessment
- Exploitation less likely
- Product family
- Windows, Windows ESU (Extended Security Updates), Microsoft Office
- Updates (KB)
- KB5131291, KB5131085, KB5131096, KB5131090, KB5131087, KB5132061
Public exploits
PoC-in-GitHub, Metasploit and Exploit-DB list nothing for this CVE.
Research sources
- Microsoft Security Update Guide: CVE-2026-113749 msrc.microsoft.com
- CVE Record CVE-2026-113749 (CNA: Microsoft) www.cve.org
- Cisco Talos: Microsoft Patch Tuesday for November 2026 blog.talosintelligence.com
- Strix AI: CVE-2026-113749 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, 05:55.
Original description (NVD)
Heap-based buffer overflow in Microsoft Windows Codecs Library 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.
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