Microsoft Office Word: Stack-based buffer overflow enables remote code execution
Summary
A stack-based buffer overflow in Microsoft Office Word allows an unauthorized attacker to execute code over a network. The attack requires a user to interact, typically by opening a crafted document, and the attack complexity is rated high. CVSS 7.5 (High); no exploitation is known at the time of this entry.
Affected
- Microsoft 365 Apps for Enterprise: 16.0.1 before the fixed build (build number not confirmed; see advisory)
- Microsoft Office 365 for Mac: 1.0.0 before 16.115.26110837
- Office LTSC 2021: 16.0.1 before 16.0.14334.21048
- Office LTSC 2024: 16.0.0 before 16.0.17932.21140 (from a third-party tracker, to be verified)
- Office LTSC for Mac 2021 and 2024: before 16.115.26110837 (from a third-party tracker, to be verified)
Fixed in
Fixes are included in the November 2026 Office security updates. Fixed build numbers per product: see the Office security release page (https://aka.ms/OfficeSecurityReleases) and the Microsoft advisory. Exact fixed build for Microsoft 365 Apps for Enterprise: Unknown.
Workaround
Unknown. No workaround was found in the available sources. Check the Microsoft advisory for interim measures.
Exploitation
- No evidence of exploitation in the wild found.
- Not listed in the CISA KEV catalog as of publication (per a third-party tracker).
- CVSS vector includes E:U (exploit code maturity: Unproven).
- Public proof of concept: Unknown.
Our recommendation
- Install the November 2026 Office security updates on all Word installations, including Microsoft 365, LTSC and Mac.
- Verify the fixed build numbers against the Microsoft advisory before rollout.
- Check LTSC and Mac installations separately, as they may not update through the same channel.
- Restrict or sandbox opening of documents from unknown senders and email attachments.
- Prioritise together with CVE-2026-111285 (heap-based overflow in Word, CVSS 8.8).
- Monitor for exploitation news and CISA KEV updates.
Information from Microsoft (Patch Tuesday November 2026)
Public exploits
PoC-in-GitHub, Metasploit and Exploit-DB list nothing for this CVE.
Research sources
- Microsoft Security Update Guide: CVE-2026-111287 msrc.microsoft.com
- CVE Record CVE-2026-111287 www.cve.org
- Strix AI: CVE-2026-111287 www.strix.ai
- CISA KEV alert, 10 Nov 2026 www.cisa.gov
- Proofpoint: document-based exploitation in 2026 www.proofpoint.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 11 Nov 2026, 06:01.
Original description (NVD)
Stack-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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