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. Exploitation requires high attack complexity and user interaction, but no privileges. CISA SSVC rates exploitation as none and not automatable, and no public exploit code or in-the-wild exploitation is known.
Affected
- Microsoft 365 Apps for Enterprise: 16.0.1 up to the fixed build (exact build unknown, see MSRC)
- Microsoft Office LTSC 2021: 16.0.1 to before 16.0.14334.21048
- Microsoft Office LTSC 2024: 16.0.0 to before 16.0.17932.21140
- Other versions (for example Access 2016/2019 or Office for Mac): Unknown, check the MSRC advisory
Fixed in
- Microsoft 365 Apps for Enterprise: Unknown, see the MSRC advisory and aka.ms/OfficeSecurityReleases
- Microsoft Office LTSC 2021: 16.0.14334.21048
- Microsoft Office LTSC 2024: 16.0.17932.21140
Workaround
Unknown.
Exploitation
- No public proof-of-concept code or in-the-wild exploitation known at the time of writing.
- CISA SSVC: exploitation none, not automatable, technical impact total.
- A third-party aggregator lists it as not in the CISA KEV catalog; not verified directly.
Our recommendation
- Install the Office security update for affected builds as soon as possible, at the latest in the next standard update cycle.
- Identify all Office installations and Access databases in use, including legacy Access files shared by email or file shares.
- Do not open Access files from unknown senders or untrusted downloads until patched.
- Monitor for public exploit code and escalate if it appears or if Access runs on internet-facing servers.
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 Response Center: CVE-2026-109498 msrc.microsoft.com
- CVE.org CNA record: CVE-2026-109498 www.cve.org
- Strix: CVE-2026-109498 (third-party aggregator) 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 11 Nov 2026, 06:03.
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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