Microsoft Office Access: Remote code execution via heap-based buffer overflow
Summary
A heap-based buffer overflow in Microsoft Office Access allows an unauthorized attacker to execute code over a network. The CVSS vector rates the attack as remote, requiring no privileges but user interaction, with full impact on confidentiality, integrity and availability. The CVE record does not describe the required user action; the sources do not confirm that it is opening a crafted Office file.
Affected
- Microsoft 365 Apps for Enterprise: from 16.0.1 before the fixed build referenced at aka.ms/OfficeSecurityReleases (build number not stated in the CVE record)
- Microsoft Office LTSC 2021: from 16.0.1 before 16.0.14334.21048
- Microsoft Office LTSC 2024: from 16.0.0 before 16.0.17932.21140
- Office 2016 and Office 2019 are not listed in the CVE record.
Fixed in
- Microsoft 365 Apps for Enterprise: Unknown. Check the MSRC advisory for the build number.
- Microsoft Office LTSC 2021: 16.0.14334.21048 or later
- Microsoft Office LTSC 2024: 16.0.17932.21140 or later
Workaround
Unknown. No workaround or mitigation is documented in the sources.
Exploitation
- No known exploitation at publication; CISA SSVC lists exploitation as none and the exploit maturity as Unproven.
- Not listed in the CISA KEV catalogue at publication. The status should be rechecked.
- No public proof of concept found. This means nothing is known so far, not that exploitation is ruled out.
Our recommendation
- Update Microsoft 365 Apps and Office LTSC to the fixed builds via the normal Office update channel, and confirm the exact build on the MSRC page.
- Inventory all Access-capable Office installations and prioritise them.
- Until patched, treat Office files from untrusted sources with caution.
- Monitor the CISA KEV catalogue for changes.
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 Record CVE-2026-109493 www.cve.org
- GitHub issue #4034 (CVE alert) github.com
- Strix CVE-2026-109493 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 10 Nov 2026, 23:53.
Original description (NVD)
Heap-based buffer overflow in Microsoft Office Access 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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