Microsoft Office Word: Heap-based buffer overflow allows remote code execution
Summary
A heap-based buffer overflow in Microsoft Office Word allows an unauthorized attacker to execute code over a network. The attack requires a user to open a crafted document, typically received by email or download, but no account or privileges on the target system are needed. NVD analysis was still pending at publication, and the listed CWE-197 has not been verified.
Affected
- Microsoft 365 Apps for Enterprise: 16.0.1 up to the fixed build (upper bound not stated as a build number)
- Microsoft Office 365 for Mac: 1.0.0 to before 16.115.26110837
- Microsoft Office LTSC 2021: 16.0.1 to before 16.0.14334.21048
- Microsoft Office LTSC 2024: 16.0.0 to before 16.0.17932.21140
- Microsoft Office LTSC for Mac 2021: 16.0.1 to before 16.115.26110837
- Microsoft Office LTSC for Mac 2024: 16.0.0 to before 16.115.26110837
Fixed in
- Microsoft 365 Apps for Enterprise: Unknown.
- Microsoft Office 365 for Mac: 16.115.26110837 or later
- Microsoft Office LTSC 2021: 16.0.14334.21048 or later
- Microsoft Office LTSC 2024: 16.0.17932.21140 or later
- Microsoft Office LTSC for Mac 2021: 16.115.26110837 or later
- Microsoft Office LTSC for Mac 2024: 16.115.26110837 or later
Workaround
Unknown. No vendor workaround has been identified. Install the November 2026 Office update.
Exploitation
- No evidence of exploitation in the wild for this CVE.
- No public proof of concept found.
- CISA SSVC: exploitation none, automatable no, technical impact total.
- Reports state that none of the November 2026 CVEs were publicly disclosed before the patch was released.
Our recommendation
- Install the November 2026 Microsoft Office and Microsoft 365 Apps updates promptly on all affected systems.
- Verify the fixed build numbers for Microsoft 365 Apps in the MSRC Security Update Guide, as they were not confirmed.
- Keep Protected View enabled for files from the internet and email attachments.
- Filter inbound Office documents at the mail gateway and train users not to open unexpected attachments.
- Monitor for unusual Office process activity, such as Word spawning command shells.
Information from Microsoft (Patch Tuesday November 2026)
Public exploits
PoC-in-GitHub, Metasploit and Exploit-DB list nothing for this CVE.
Research sources
- MSRC Security Update Guide: CVE-2026-112721 msrc.microsoft.com
- Strix: CVE-2026-112721 (CNA data mirror) www.strix.ai
- Qualys: Microsoft Patch Tuesday November 2026 review blog.qualys.com
- Tenable: Microsoft November 2026 Patch Tuesday www.tenable.com
- NT Compatible: Microsoft November 2026 Patch Tuesday www.ntcompatible.com
- VulDB: CVE-2026-116720 (possible duplicate, to be confirmed) vuldb.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 10 Nov 2026, 23:01.
Original description (NVD)
Heap-based buffer overflow in Microsoft Office Word 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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