Microsoft Office Word: Out-of-bounds read leads to remote code execution
Summary
Microsoft Office Word contains an out-of-bounds read vulnerability that allows an unauthorized attacker to execute code over a network. Exploitation requires that a user opens a crafted document, for example from an email attachment or a file share. Microsoft rates the impact as high for confidentiality, integrity and availability (CVSS 3.1 base score 8.8).
Affected
- Microsoft 365 Apps for Enterprise: 16.0.1 before the fixed build listed on the Office security releases page
- 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 (unverified, 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
- Microsoft 365 Apps for Enterprise: Unknown. Check the Office security releases page at https://aka.ms/OfficeSecurityReleases
- Office 365 for Mac: 16.115.26110837
- Office LTSC 2021: 16.0.14334.21048
- Office LTSC 2024: Unverified. A third-party source lists 16.0.17932.21140, not confirmed by Microsoft.
- Office LTSC for Mac 2021 and 2024: 16.115.26110837
Workaround
Unknown.
- No vendor mitigation is documented for this CVE. Patching is the expected fix.
Exploitation
- No evidence of exploitation in the wild found.
- No public proof-of-concept found.
- CVSS exploit code maturity is unproven (E:U).
- NVD status at publication: Awaiting Analysis.
Our recommendation
- Install the November 2026 Office security updates on all affected installations as soon as possible, prioritizing mail-facing and file-sharing systems.
- Check LTSC and managed installations, which are often updated later than Microsoft 365 Apps with cloud updates.
- Verify the fixed build numbers against the MSRC advisory before relying on them.
- Until patched, consider restricting or sandboxing untrusted Office attachments (own recommendation, not from the vendor).
- Monitor for exploitation indicators and unusual Word process activity.
Information from Microsoft (Patch Tuesday November 2026)
Public exploits
PoC-in-GitHub, Metasploit and Exploit-DB list nothing for this CVE.
Research sources
- CVE.org record CVE-2026-109501 www.cve.org
- Microsoft Security Update Guide (MSRC advisory) msrc.microsoft.com
- Tenable: November 2026 Patch Tuesday www.tenable.com
- Strix.ai CVE-2026-109501 (aggregator, cross-check only) www.strix.ai
- NewsBeep: Patch Tuesday list www.newsbeep.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, 23:51.
Original description (NVD)
Out-of-bounds read 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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