Microsoft Office Access: Heap-based buffer overflow enables remote code execution
Summary
A heap-based buffer overflow in Microsoft Office Access allows an unauthenticated attacker to execute code remotely. Exploitation requires a user to open a crafted Access file, for example one received by email. The CVSS 3.1 base score is 8.8 (High).
Affected
- Microsoft 365 Apps for Enterprise (Current Channel, Monthly Enterprise Channel and Semi-Annual Channel; exact ranges disputed between sources, see recommendation)
- Microsoft Office LTSC 2021: versions 16.0.1 to below 16.0.14334.20974
- Microsoft Office LTSC 2024: versions 16.0.0 to below 16.0.17932.21056 (per one secondary source, not confirmed by Microsoft)
Fixed in
- Microsoft 365 Apps Current Channel: 16.0.20430.20182 or later (per secondary mirror)
- Microsoft 365 Apps Monthly Enterprise Channel: 16.0.20430.20180, 16.0.20326.20232 or 16.0.20228.20276 (per secondary mirror and Microsoft release notes)
- Office LTSC 2021: 16.0.14334.20974 or later
- Office LTSC 2024 and Semi-Annual Channel: Unknown. Sources conflict; verify in the MSRC advisory.
Workaround
Unknown. No vendor workaround found. Patching is the primary fix.
Exploitation
- CISA KEV: not listed.
- Exploited in the wild: no evidence found in the sources.
- Public proof of concept: none found; treat as unknown.
- EPSS: about 0.0076 (low).
- CISA SSVC: exploitation none, automatable no, technical impact total.
Our recommendation
- Identify all systems with Microsoft Access installed, including Microsoft 365 Apps and Office LTSC, and check each client's update channel and build number.
- Install the October 2026 security updates on these systems first, and confirm the build against the MSRC advisory, since the sources conflict for some channels.
- Until patched, do not open Access files (.accdb, .mdb) from untrusted sources, and block or quarantine such attachments at the mail gateway.
- Keep Protected View enabled and warn users about unexpected database attachments.
- Monitor for unusual Access activity and phishing campaigns that use database files.
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 Response Center advisory msrc.microsoft.com
- NVD mirror (Vulners) vulners.com
- Microsoft version ranges mirror (Vulners) vulners.com
- Microsoft 365 Apps security update release notes learn.microsoft.com
- Strix CVE page www.strix.ai
- GitHub CVE tracking issue 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, 19:14.
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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