Microsoft Office Word: Local privilege escalation via stack-based buffer overflow
Summary
A stack-based buffer overflow in Microsoft Office Word allows a locally authorized attacker to elevate privileges. Affected are Microsoft 365 Apps for Enterprise, Office 365 for Mac, and Office LTSC 2021, LTSC 2024 and LTSC for Mac editions. The CVSS 3.1 base score is 7.8 (High), and the attacker needs a low-privilege account or local code execution, which makes this a second-stage risk often chained with phishing.
Affected
- Microsoft 365 Apps for Enterprise: 16.0.1 up to the fixed build (exact fixed build not stated in the sources)
- Office 365 for Mac: versions before 16.114.26101123
- Office LTSC 2021: versions from 16.0.1 before 16.0.14334.20974
- Office LTSC 2024: versions from 16.0.0 before 16.0.17932.21056
- Office LTSC for Mac 2021: versions from 16.0.1 before 16.114.26101123
- Office LTSC for Mac 2024: versions from 16.0.0 before 16.114.26101123
Fixed in
- Install the latest Office security update released in October 2026, which Microsoft states fixes CVE-2026-96995.
- Office LTSC for Mac 2021 and 2024: updates were not yet available at the time of the sources; check the MSRC advisory for release status.
Workaround
- Unknown. No vendor workaround was found in the sources; patching is the expected remedy.
Exploitation
- Not listed in CISA KEV.
- CISA SSVC data rates exploitation as none and automatable as no.
- No public proof of concept was found in the research; this does not rule one out.
- No reports of exploitation in the wild were found.
Our recommendation
- Install the latest October 2026 Microsoft 365 and Office security updates on all Windows and Mac clients.
- Ensure Mac fleets receive the LTSC or 365 builds once they are released.
- Check the MSRC advisory for exact build numbers before rollout.
- Prioritise patching where phishing with Office documents is a risk, and monitor KEV and proof-of-concept status.
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 Update Guide: CVE-2026-96995 msrc.microsoft.com
- OpenCVE: CVE-2026-96995 app.opencve.io
- Vulners: CVE-2026-96995 (CNA record) vulners.com
- Microsoft Office for Mac release notes learn.microsoft.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 2 Nov 2026, 00:34.
Original description (NVD)
Stack-based buffer overflow in Microsoft Office Word allows an authorized attacker to elevate privileges locally.
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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