Microsoft Office Excel: Remote code execution via buffer underflow
Summary
A buffer underflow (CWE-124) in Microsoft Office Excel allows an unauthorized attacker to execute code over a network. The attacker needs a crafted file that the user opens, for example from an email or a download. Successful exploitation could affect confidentiality, integrity and availability of the affected system.
Affected
- Microsoft 365 Apps for Enterprise (16.0.1 up to the fixed build, per Microsoft's release page)
- Office 365 for Mac: before 16.114.26101123
- Office LTSC 2021: before 16.0.14334.20974
- Office LTSC 2024: before 16.0.17932.21056
- Office LTSC for Mac 2021 and 2024: before 16.114.26101123 (LTSC for Mac 2024 starts at 16.0.0)
- Office Online Server: before 16.0.10417.20228
Fixed in
- Office LTSC 2021: 16.0.14334.20974 and later
- Office LTSC 2024: 16.0.17932.21056 and later
- Office 365 for Mac: 16.114.26101123 and later
- Office Online Server: 16.0.10417.20228 and later (October 2026 update, KB5002928)
- Microsoft 365 Apps (Click-to-Run): fixed build unknown, see MSRC
- Office LTSC for Mac 2021/2024: fixed build unknown, see MSRC
Workaround
Unknown. No vendor workaround for this CVE was found. General hardening such as keeping Protected View enabled and restricting attachments from untrusted senders reduces risk, but these are not confirmed mitigations for this CVE.
Exploitation
- Exploited in the wild: no evidence found.
- CISA KEV: not listed.
- CISA SSVC: exploitation none, automatable no, technical impact total.
- Public proof of concept: none found.
Our recommendation
- Inventory Excel versions and build numbers, including Office Online Server, and compare them with the fixed builds above.
- Install the October 2026 security updates for Microsoft 365 Apps, LTSC and Office Online Server, and verify the exact builds on MSRC.
- Check whether Office Online Server is exposed to the internet and patch or restrict it first.
- Restrict or scan attachments from external senders at the mail gateway and keep Protected View enabled.
- Monitor for unusual Excel processes spawning scripts or shells.
Information from Microsoft (Patch Tuesday October 2026)
- Severity (Microsoft)
- Important
- Impact
- Remote code execution – Microsoft Office Excel
- Status on Patch Tuesday
- Neither exploited nor publicly disclosed
- Exploitability assessment
- Exploitation less likely
- Product family
- Microsoft Office
- Updates (KB)
- KB5002928
Public exploits
PoC-in-GitHub, Metasploit and Exploit-DB list nothing for this CVE.
Research sources
- Microsoft Security Update Guide: CVE-2026-97008 msrc.microsoft.com
- OpenCVE: CVE-2026-97008 app.opencve.io
- Vulners CVE list: CVE-2026-97008 vulners.com
- Microsoft Support: KB5002928 Office Online Server update support.microsoft.com
- VulDB: vuln 419701 vuldb.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 31 Oct 2026, 17:50.
Original description (NVD)
Buffer underwrite ('buffer underflow') in Microsoft Office Excel 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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