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 over a network. Exploitation requires that a user opens a crafted Word document, typically delivered by phishing email or a shared link. Successful exploitation would run code in the context of the user, with high impact on confidentiality, integrity and availability.
Affected
- Microsoft 365 Apps for Enterprise: affected from 16.0.1 before the fixed build (see MSRC; CVE record links to aka.ms/OfficeSecurityReleases)
- Microsoft Office 365 for Mac: 1.0.0 to before 16.115.26110837
- Microsoft Office LTSC 2021: 16.0.1 to before 16.0.14334.21048
- Unverified, reported by a third-party mirror only: Office LTSC 2024 (fixed in 16.0.17932.21140), Office LTSC for Mac 2021 and 2024 (fixed in 16.115.26110837)
Fixed in
- Microsoft security update via Office update channels
- Microsoft 365 Apps for Enterprise: Unknown (check MSRC)
- Office 365 for Mac: 16.115.26110837 or later
- Office LTSC 2021: 16.0.14334.21048 or later
- Office LTSC 2024: 16.0.17932.21140 or later (unverified)
Workaround
No vendor workaround identified.
- Keep Protected View enabled for files from the internet or email.
- Block or quarantine untrusted Office attachments at the mail gateway.
Exploitation
- No confirmed exploitation in the wild known at the time of writing.
- No public proof-of-concept code found.
- CISA KEV listing: not found. Check Microsoft's Exploitation Detected flag on the MSRC page.
- CISA SSVC: exploitation none, not automatable, total technical impact.
Our recommendation
- Update Microsoft 365 Apps, Office LTSC and Office for Mac to the fixed builds in the next patch cycle, sooner if exploitation is reported.
- Prioritise systems with LTSC 2021 or Mac builds that may not update automatically.
- Verify exact fixed builds on the MSRC advisory before rollout.
- Restrict local admin rights and monitor for Word spawning unexpected processes.
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 (MSRC) msrc.microsoft.com
- CVE.org CVE Record www.cve.org
- Microsoft November 2026 Patch Tuesday summary cybersecuritynews.com
- Strix CVE mirror www.strix.ai
- CWE-122: Heap-based Buffer Overflow cwe.mitre.org
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, 23:15.
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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