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. The attack requires that a user opens a manipulated document, for example one received by email or download. Microsoft rates the flaw as Important with a CVSS score of 8.8, and no public exploit or known exploitation exists.
Affected
- Microsoft 365 Apps for Enterprise: 16.0.1 up to the fixed build (exact fixed build unknown, see Microsoft advisory)
- 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 and later
- Microsoft Office LTSC 2024: 16.0.17932.21056 and later
- Microsoft 365 Apps for Enterprise: October 2026 security updates (fixed build not confirmed, check the Microsoft page)
- Note: the fix was omitted from the October 2026 release notes; verify the installed build
Workaround
Unknown. No vendor workaround was found. The Preview Pane is not an attack vector according to Microsoft.
Exploitation
- Not publicly disclosed and not known to be exploited (Microsoft)
- Not listed in the CISA KEV catalogue
- CISA SSVC: exploitation none, not automatable
- EPSS below 1%
- No public proof of concept found
Our recommendation
- Install the October 2026 Microsoft Office updates on all Office clients
- Verify the installed build against the fixed builds, not only the update label
- Check the Microsoft Security Update Guide page for the exact M365 Apps fixed build
- Filter suspicious email attachments and restrict macros and downloads from untrusted sources
- Train users not to open unexpected Word documents
- Monitor for unusual Word process behaviour on endpoints
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-2026-108450 msrc.microsoft.com
- OpenCVE: CVE-2026-108450 app.opencve.io
- VulDB: CVE-2026-108450 vuldb.com
- ThreatInt: CVE-2026-108450 cve.threatint.com
- Strix: CVE-2026-108450 www.strix.ai
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)
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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