Microsoft Word: Heap-based buffer overflow enables remote code execution
Summary
A heap-based buffer overflow in Microsoft Word allows code execution on the affected system. An unauthenticated attacker can exploit it over the network, but a user must open a crafted document, for example one delivered by email or file sharing. The CVSS 3.1 base score is 8.8 (High).
Affected
- Microsoft 365 Apps for Enterprise: 16.0.1 up to the build listed at aka.ms/OfficeSecurityReleases
- 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 the fixed build (see Fixed)
- 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 for Mac and Office LTSC for Mac: 16.115.26110837
- Office LTSC 2024: Unverified. A secondary source states 16.0.17932.21140; not confirmed by the vendor record.
- Microsoft 365 Apps for Enterprise: build listed at aka.ms/OfficeSecurityReleases; exact build unknown.
Workaround
Unknown. No vendor workaround found; the security update is the remedy.
Exploitation
- No evidence of exploitation in the wild.
- No public proof of concept found.
- CISA SSVC: exploitation none, automatable no, technical impact total.
Our recommendation
- Install the Office security updates from 10 November 2026 on all Office editions, including Mac and LTSC.
- Verify the exact fixed builds at MSRC and aka.ms/OfficeSecurityReleases before relying on them.
- Until patched, restrict or sandbox Word files from untrusted email and downloads, and keep Protected View enabled.
- Train users not to open unexpected Word documents.
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-2026-110055 msrc.microsoft.com
- CVE Record: CVE-2026-110055 www.cve.org
- Microsoft Security Update Guide: CVE-2026-110050 (sibling advisory) msrc.microsoft.com
- Zero Day Initiative: November 2026 Security Update Review www.zerodayinitiative.com
- Qualys: Microsoft Patch Tuesday November 2026 blog.qualys.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, 23:43.
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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