Microsoft Office Word: Remote code execution via heap-based buffer overflow
Summary
A heap-based buffer overflow in Microsoft Word allows an unauthenticated attacker to execute code over a network. The attack requires a user to open a crafted Word document, for example one received by email or from shared storage, and the code runs with the rights of the logged-in user. The CVSS 3.1 base score is 8.8 (High), based on the CNA record.
Affected
- Microsoft 365 Apps for Enterprise: from 16.0.1, fixed build not stated in the CVE record
- Microsoft Office LTSC 2021: from 16.0.1 before 16.0.14334.20974
- Microsoft Office LTSC 2024: from 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 Microsoft's Office security release page and current Microsoft 365 release notes.
Workaround
- Unknown. No vendor-published mitigation found; the patch is the remedy.
- Interim until patched (general guidance, not from the sources): keep Protected View enabled for internet and email attachments, and filter or quarantine suspicious Word attachments at the mail gateway.
Exploitation
- No evidence of in-the-wild exploitation found.
- CISA SSVC (Vulnrichment): exploitation none, automatable no.
- Not listed in CISA KEV in the tracker snapshots reviewed (not a live check).
- No public proof of concept found; this does not prove none exists.
- EPSS: Unknown.
- VulDB's exploit price estimate (USD 5k to 25k) is a market figure, not evidence of exploitation.
Our recommendation
- Patch Microsoft 365 Apps and Office LTSC 2021/2024 clients to the fixed builds in the normal high-severity cycle; for M365 Apps, confirm the build against Microsoft's release notes.
- Verify the vendor advisory before rollout, since the fixed build for M365 Apps was not confirmed from the MSRC page.
- Keep Protected View enabled and handle external Word documents with caution, especially on unpatched clients.
- Monitor mail gateway and endpoint logs for suspicious Word attachments.
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 Update Guide: CVE-2026-108437 msrc.microsoft.com
- OpenCVE: CVE-2026-108437 app.opencve.io
- VulDB: CVE-2026-108437 (420918) vuldb.com
- OffSeq Radar: CVE-2026-108437 radar.offseq.com
- ThreatIntel: CVE-2026-108437 cve.threatint.com
- Red Packet Security: CVE-2026-108437 alert www.redpacketsecurity.com
- Strix AI: CVE-2026-108437 www.strix.ai
- GitHub issue: astruzocyber/CVE #2080 github.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, 16:20.
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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