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. The attack requires a user to open a crafted document, for example one received by email or from a file share. The CVSS base score is 8.8 (High), and the attacker needs no privileges.
Affected
- Microsoft 365 Apps for Enterprise: 16.0.1 up to the fixed build (exact build: see MSRC advisory)
- Microsoft Office 365 for Mac: before 16.115.26110837
- Microsoft Office LTSC 2021: before 16.0.14334.21048
- Microsoft Office LTSC 2024: before 16.0.17932.21140 (unverified, check MSRC)
- Microsoft Office LTSC for Mac 2021 and 2024: before 16.115.26110837
Fixed in
- Microsoft November 2026 security updates for Microsoft 365 Apps, Office LTSC and Office for Mac
- Microsoft 365 Apps for Enterprise: fixed build unknown from the available sources, see MSRC advisory
- Office LTSC 2024 (Windows): build number to be verified on MSRC
Workaround
- No vendor-documented workaround found. Patching is the recommended fix.
- General measures: keep Protected View enabled, block or sandbox macro-free attachments from unknown senders.
Exploitation
- Exploited in the wild: No evidence found. CISA KEV listing not verified.
- Public proof of concept: None found.
- Microsoft temporal score: exploit maturity unproven (E:U).
Our recommendation
- Patch Microsoft 365 Apps, Office LTSC and Office for Mac clients with the November 2026 updates as a priority.
- Confirm the fixed build for each product on the MSRC advisory before rollout.
- Keep Protected View enabled and restrict documents from unknown senders.
- Monitor the CISA KEV catalog for a listing of this CVE.
Information from Microsoft (Patch Tuesday November 2026)
Public exploits
PoC-in-GitHub, Metasploit and Exploit-DB list nothing for this CVE.
Research sources
- CVE Record CVE-2026-116720 www.cve.org
- Microsoft Security Update Guide CVE-2026-116720 msrc.microsoft.com
- Tenable: Microsoft November 2026 Patch Tuesday www.tenable.com
- Strix AI CVE-2026-116720 www.strix.ai
- VulDB CVE-2026-116720 (conflicting data) 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, 22:38.
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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