Microsoft Office Word: Heap-based buffer overflow enables remote code execution
Summary
A heap-based buffer overflow in Microsoft Office Word allows an unauthorized attacker to execute code remotely. User interaction is required, so the user must open a crafted document, typically one received as an email attachment or download. CVSS 3.1 rates the flaw 8.8 (high). Microsoft has not reported known exploitation at publication.
Affected
- Microsoft 365 Apps for Enterprise (32-bit and x64): from 16.0.1, before the fixed build (not stated in the CNA record)
- Microsoft Office 365 for Mac: from 1.0.0, before 16.115.26110837
- Microsoft Office LTSC 2021: from 16.0.1, before 16.0.14334.21048
- Microsoft Office LTSC 2024: from 16.0.0, before 16.0.17932.21140 (third-party figure, unverified)
- Microsoft Office LTSC for Mac 2021: from 16.0.1, before 16.115.26110837
- Microsoft Office LTSC for Mac 2024: from 16.0.0, before 16.115.26110837
Fixed in
- Microsoft 365 Apps for Enterprise: Unknown.
- Office 365 for Mac and LTSC for Mac 2021/2024: 16.115.26110837 (per CNA record)
- Office LTSC 2021: 16.0.14334.21048 (per CNA record)
- Office LTSC 2024: 16.0.17932.21140 (third-party, unverified)
Workaround
- Unknown. No vendor workaround is documented.
- Until patched, restrict Office updates to the vendor channel and block or quarantine Word documents from unknown senders.
Exploitation
- Microsoft rates exploit code maturity as Unproven (E:U) at publication.
- No reports of exploitation in the wild or public proof of concept found.
- CISA KEV status: unconfirmed.
- CISA SSVC: exploitation none, automatable no, technical impact total.
Our recommendation
- Check which Office channel and build each client runs (Microsoft 365 Apps, Mac, LTSC 2021/2024).
- Verify fixed builds on the Microsoft Security Update Guide before rollout, especially for Microsoft 365 Apps and LTSC 2024.
- Patch Microsoft 365/Office clients in the next regular update cycle, or sooner if phishing with Office attachments has been observed.
- Warn users not to open Word documents from unknown senders and monitor for suspicious document attachments.
- Recheck the CISA KEV catalogue and NVD, which still show analysis pending.
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-2026-112726 msrc.microsoft.com
- CVE Record: CVE-2026-112726 www.cve.org
- Strix AI: CVE-2026-112726 (third-party) www.strix.ai
- Qualys: Microsoft Patch Tuesday November 2026 review blog.qualys.com
- Zero Day Initiative: November 2026 security update review www.zerodayinitiative.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, 22:55.
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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