Microsoft Office Word: Heap-based buffer overflow allows remote code execution
Summary
A heap-based buffer overflow in Microsoft Office Word allows an unauthenticated attacker to execute code over a network. The attack requires a user to open a manipulated document, so the main risk is malicious files delivered by email or file sharing. The CVSS 3.1 base score is 8.8 (High).
Affected
- Microsoft 365 Apps for Enterprise: 16.0.1 up to the build listed at aka.ms/OfficeSecurityReleases
- Office 365 for Mac: 1.0.0 to before 16.115.26110837
- Office LTSC 2021: 16.0.1 to before 16.0.14334.21048
- Office LTSC 2024: 16.0.0 to before 16.0.17932.21140
- Office LTSC for Mac 2021: 16.0.1 to before 16.115.26110837
- Office LTSC for Mac 2024: 16.0.0 to before 16.115.26110837
Fixed in
- Microsoft 365 Apps for Enterprise: Unknown (see aka.ms/OfficeSecurityReleases and the MSRC advisory)
- Office 365 for Mac: 16.115.26110837 or later
- Office LTSC 2021: 16.0.14334.21048 or later
- Office LTSC 2024: 16.0.17932.21140 or later
- Office LTSC for Mac 2021 and 2024: 16.115.26110837 or later
Workaround
Unknown. No vendor-published workaround was found.
- Keep Protected View enabled.
- Block or quarantine unexpected Word attachments from external senders.
Exploitation
- Exploited in the wild: No evidence found.
- CISA SSVC: Exploitation none, Automatable no, Technical Impact total.
- Public proof-of-concept exploit: None found.
- CVSS exploit code maturity: Unproven.
Our recommendation
- Install the security updates for all affected Microsoft 365 Apps, Office LTSC and Office for Mac installations as soon as possible.
- Verify the installed build numbers against the fixed versions listed above.
- Until patched, restrict Word documents from untrusted senders and keep Protected View enabled.
- Monitor for unusual Word process behaviour and review mail gateway logs for suspicious attachments.
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 advisory CVE-2026-111307 msrc.microsoft.com
- CVE.org record CVE-2026-111307 www.cve.org
- CWE-122 definition (MITRE) cwe.mitre.org
- Microsoft November 2026 Patch Tuesday overview (Cybersecurity News) cybersecuritynews.com
- November 2026 security update review (Zero Day Initiative) www.zerodayinitiative.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, 23:08.
Original description (NVD)
Heap-based buffer overflow 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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