Microsoft Office Word: Heap-based buffer overflow allows remote code execution
Summary
A heap-based buffer overflow in Microsoft Word, part of Microsoft 365 Apps and Office LTSC suites, can be abused by an unauthenticated attacker over the network. Exploitation requires a user to open a crafted document, for example one received by email or downloaded from the internet. A successful attack could lead to arbitrary code execution with high impact on confidentiality, integrity and availability.
Affected
- Microsoft 365 Apps for Enterprise (32-bit and x64): from 16.0.1, before the fix build (fixed build not stated in the CVE record)
- Microsoft Office 365 for Mac: from 1.0.0 before 16.115.26110837
- Microsoft Office LTSC 2021 (32-bit and x64): from 16.0.1 before 16.0.14334.21048
- Microsoft Office LTSC 2024 (32-bit and x64): from 16.0.0, fixed build unconfirmed
- Microsoft Office LTSC for Mac 2021 and 2024: from 16.0.0 / 16.0.1 before 16.115.26110837
Fixed in
- Microsoft Office LTSC 2021: 16.0.14334.21048
- Microsoft Office 365 for Mac and LTSC for Mac: 16.115.26110837 (per CVE record for Office 365 for Mac)
- Microsoft 365 Apps for Enterprise and Office LTSC 2024: Unknown. Check the MSRC advisory for the exact build.
Workaround
Unknown. No vendor-published workaround was found for this CVE. Until patched, restrict opening untrusted attachments and keep Protected View enabled.
Exploitation
- Exploited in the wild: no evidence found (CVSS temporal exploit maturity: Unproven)
- Public proof-of-concept: none found
- SSVC: not automatable, total technical impact
Our recommendation
- Check the exact fixed builds for your Microsoft 365 and Office LTSC versions in the MSRC advisory and install the November 2026 updates.
- Prioritise internet-facing mail and document workflows.
- Until patched, do not open unsolicited or untrusted Word documents and keep Protected View enabled.
- Verify the CVSS score and affected versions once NVD has completed its analysis.
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: CVE-2026-111310 msrc.microsoft.com
- CVE Record CVE-2026-111310 www.cve.org
- Strix: CVE-2026-111310 (unverified aggregator data) www.strix.ai
- CWE-122: Heap-based Buffer Overflow cwe.mitre.org
- Zero Day Initiative: November 2026 Security Update Review 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, 23:03.
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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