Microsoft Office Access: Heap-based buffer overflow allows remote code execution
Summary
Microsoft Office Access in Microsoft 365 Apps for Enterprise and Office LTSC 2021 and 2024 contains a heap-based buffer overflow. An unauthorized attacker can execute code over a network. The attack requires that a user interacts with the attacker's content, for example by opening a crafted file, but no login is required. The CVSS base score of 8.8 comes from the CNA (Microsoft); NVD analysis was still pending at publication.
Affected
- Microsoft 365 Apps for Enterprise: 16.0.1 onwards, exact fixed build unknown (see MSRC advisory)
- Office LTSC 2021: 16.0.1 before 16.0.14334.21048
- Office LTSC 2024: 16.0.0 before 16.0.17932.21140
Fixed in
- Office LTSC 2021: 16.0.14334.21048 and later
- Office LTSC 2024: 16.0.17932.21140 and later
- Microsoft 365 Apps for Enterprise: Unknown. Check the Microsoft release page (aka.ms/OfficeSecurityReleases) and the MSRC advisory.
Workaround
Unknown. No vendor workaround found; applying the security update is the realistic path.
Exploitation
- No exploitation in the wild found at time of research.
- No public proof of concept found.
- Not listed in CISA KEV (per Strix).
- CISA SSVC assessment: Exploitation none, Automatable no, Technical Impact total.
Our recommendation
- Install the November 2026 Office security updates on all systems with Access or Microsoft 365 Apps.
- Verify the installed build against the MSRC advisory, because the fixed Microsoft 365 build is not confirmed.
- Make sure the October 2026 updates are installed as well, since other Access RCE CVEs were disclosed then.
- Treat unsolicited Office files from external senders with caution until patched.
- Priority: high for SMEs that use Access or share Office files on fileservers, otherwise medium.
Information from Microsoft (Patch Tuesday November 2026)
Public exploits
PoC-in-GitHub, Metasploit and Exploit-DB list nothing for this CVE.
Research sources
- MSRC Security Update Guide: CVE-2026-111305 msrc.microsoft.com
- CVE.org record CVE-2026-111305 www.cve.org
- Strix summary CVE-2026-111305 www.strix.ai
- Cybersecuritynews: Microsoft November 2026 Patch Tuesday cybersecuritynews.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, 23:06.
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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