Microsoft Office Excel: Remote code execution vulnerability
Summary
A heap-based buffer overflow in Microsoft Office Excel allows an unauthorized attacker to execute code on the affected computer. The attack requires a user to open a malicious spreadsheet, and the CVSS vector is local with user interaction. If exploited, the attacker can run code in the context of the logged-in user, which is a high-impact outcome.
Affected
- Microsoft 365 Apps for Enterprise: 16.0.1 to the fixed build, which the sources do not confirm (Unknown.)
- Office LTSC 2021: before 16.0.14334.20974 (third-party value, not yet verified against MSRC)
- Office LTSC 2024: before 16.0.17932.21056 (third-party value, not yet verified against MSRC)
Fixed in
- Install the latest Microsoft Office security update for your channel. Microsoft's advisory lists the fixed builds.
- Microsoft 365 Apps: fixed build Unknown.
- Office LTSC 2021 and LTSC 2024: build thresholds as listed above.
Workaround
- No vendor workaround found in the sources. Check the Microsoft advisory for mitigations.
- Interim measures (recommendation, not from a source): restrict macros and external content, block untrusted Excel attachments at the mail gateway, and keep Protected View enabled.
Exploitation
- Microsoft rates exploit code maturity as unproven.
- CISA SSVC data lists exploitation as none and automatable as no.
- The CVE is not in the CISA KEV catalog.
- No public proof of concept was found; monitor for changes.
Our recommendation
- Patch Microsoft 365 and Office clients in the next regular update cycle, prioritizing systems that open external files.
- Verify installed Office build numbers against the Microsoft advisory.
- Keep Protected View and macro restrictions enabled.
- Monitor for anomalous Office behavior and re-check CISA KEV and public exploit sources after patch release.
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-2026-97009 msrc.microsoft.com
- OpenCVE: CVE-2026-97009 app.opencve.io
- Microsoft 365 Apps security updates learn.microsoft.com
- Strix: CVE-2026-97009 www.strix.ai
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, 00:33.
Original description (NVD)
Heap-based buffer overflow in Microsoft Office Excel allows an unauthorized attacker to execute code 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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