Microsoft Office Word: Remote code execution due to numeric truncation
Summary
A numeric truncation error in Microsoft Office Word allows an unauthorized remote attacker to execute code on an affected computer. User interaction is required (CVSS UI:R), so the attack most likely relies on a crafted file delivered by email or document sharing. The CVSS base score is 8.8 (high), with high impact on confidentiality, integrity and availability.
Affected
- Microsoft 365 Apps for Enterprise: 16.0.1 up to the fixed build in the Microsoft release notes (exact build unknown)
- Microsoft Office LTSC 2021: 16.0.1 before 16.0.14334.20974
- Microsoft Office LTSC 2024: 16.0.0 before 16.0.17932.21056
Fixed in
- Microsoft Office LTSC 2021: 16.0.14334.20974
- Microsoft Office LTSC 2024: 16.0.17932.21056
- Microsoft 365 Apps for Enterprise: Unknown. Check the Microsoft 365 release notes for the October 2026 build.
Workaround
Unknown. No workaround or mitigation was found, so installing the security update is the remedy.
Exploitation
- CISA SSVC: exploitation none, automatable no, technical impact total
- Not listed in the CISA KEV catalogue
- No public proof of concept or in-the-wild exploitation found
- EPSS: unknown
Our recommendation
- Roll out the October 2026 Office updates to all client machines and verify the build number on each
- Confirm the Microsoft 365 build number and the Mac status on the MSRC page
- Prioritise this update above routine updates because of the CVSS score and the common email attack path
- Remind users not to open Word documents from unknown or unexpected senders
Information from Microsoft (Patch Tuesday October 2026)
Public exploits
PoC-in-GitHub, Metasploit and Exploit-DB list nothing for this CVE.
Research sources
- Microsoft Security Response Center: CVE-2026-108451 msrc.microsoft.com
- OpenCVE: CVE-2026-108451 app.opencve.io
- Threatint: CVE-2026-108451 cve.threatint.com
- OffSeq Radar: CVE-2026-108451 radar.offseq.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 31 Oct 2026, 16:17.
Original description (NVD)
Numeric truncation error 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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