Microsoft Word: Heap-based buffer overflow with remote code execution
Summary
A heap-based buffer overflow in Microsoft Word allows an unauthenticated attacker to execute code over a network. The attack requires a user to open a malicious document, most likely received by email or download. The CVSS score is 8.8 (HIGH), and the CNA rates the impact on confidentiality, integrity and availability as high.
Affected
- Microsoft 365 Apps for Enterprise (16.0.1 until the fixed build, exact build unknown)
- Office 365 for Mac (1.0.0 before 16.115.26110837)
- Office LTSC 2021 (16.0.1 before 16.0.14334.21048)
- Office LTSC 2024 (16.0.0 until the fixed build, exact build unknown)
- Office LTSC for Mac 2021 and 2024 (16.0.0 or 16.0.1 before 16.115.26110837)
- Other Office versions: unknown, check the Microsoft advisory
Fixed in
- Office 365 for Mac: 16.115.26110837
- Office LTSC 2021: 16.0.14334.21048
- Office LTSC for Mac 2021 and 2024: 16.115.26110837
- Microsoft 365 Apps for Enterprise: Unknown.
- Office LTSC 2024: Unknown.
Workaround
Unknown. Microsoft recommends installing the update. No official workaround was found.
Exploitation
- No exploitation in the wild found for this CVE at the time of writing.
- No public proof of concept found.
- CVSS temporal vector shows exploit code maturity Unproven (E:U).
- The actively exploited Outlook zero-day in the same release is a different CVE.
Our recommendation
- Install the November 2026 Microsoft Office security update on all affected clients as part of the normal monthly cycle, and sooner for users who handle external documents.
- Verify installed Office builds against the Microsoft advisory, including LTSC 2024 and Microsoft 365 Apps.
- Until patched, block or quarantine Office files from untrusted senders and keep Protected View enabled.
- Monitor for new exploitation reports and recheck the NVD analysis in the coming days.
Information from Microsoft (Patch Tuesday November 2026)
Public exploits
PoC-in-GitHub, Metasploit and Exploit-DB list nothing for this CVE.
Research sources
- CVE Record (CNA: Microsoft) www.cve.org
- Microsoft Security Update Guide msrc.microsoft.com
- BleepingComputer: Microsoft November 2026 Patch Tuesday www.bleepingcomputer.com
- Qualys: Microsoft Patch Tuesday November 2026 review blog.qualys.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, 23:48.
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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