Microsoft Office Word: Remote Code Execution through heap-based buffer overflow
Summary
A heap-based buffer overflow (CWE-122) in Microsoft Word allows an attacker to execute code. The attack requires local access and a user who opens a crafted document, so it is typically delivered by phishing or a malicious file. No privileges are needed, and a successful attack would have a high impact on confidentiality, integrity and availability.
Affected
- Microsoft 365 Apps for Enterprise: 16.0.1 up to the fix in the Microsoft update reference
- 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 (unconfirmed, not verified against Microsoft)
- Office LTSC for Mac 2021: 16.0.1 before 16.115.26110837
- Office LTSC for Mac 2024: 16.0.0 before 16.115.26110837
Fixed in
- Office LTSC 2021: 16.0.14334.21048
- Office 365 for Mac and Office LTSC for Mac: 16.115.26110837
- Microsoft 365 Apps for Enterprise: build not stated in the CVE record, see the Microsoft Security Update Guide
- Office LTSC 2024: unconfirmed, check the Microsoft Security Update Guide
Workaround
Unknown.
Exploitation
- No known exploitation in the wild at the time of publication.
- No public proof of concept found.
- CISA SSVC: exploitation none, automatable no, technical impact total.
- Microsoft rates exploit code maturity as Unproven.
- Not listed in the CISA KEV catalogue (as of the research date). NVD analysis is still pending.
Our recommendation
- Install the Microsoft 365 and Office security updates in the next update cycle, and prioritise them if users regularly open external documents.
- Check the Microsoft Security Update Guide for the exact fixed build of each product and for any mitigation.
- Keep Protected View and macro restrictions enabled for files from untrusted sources.
- Train users not to open unexpected Word attachments.
- Re-check the Microsoft advisory and NVD in a few days, as the record is new.
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-2026-110056 msrc.microsoft.com
- CVE Record CVE-2026-110056 (CVE Program) www.cve.org
- Strix CVE summary CVE-2026-110056 (third party, unverified fixed versions) 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, 04:24.
Original description (NVD)
Heap-based buffer overflow in Microsoft Office Word allows an unauthorized attacker to execute code 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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