Microsoft Office Excel: Remote code execution via use after free
Summary
A use-after-free weakness in Microsoft Office Excel allows an unauthorized attacker to execute code over a network. The attack requires that a user opens a malicious workbook, for example one received by email or downloaded from the internet. The CVSS base score is 8.8 (High), and the vendor rates the temporal score lower because exploit code maturity is unproven.
Affected
- Microsoft 365 Apps for Enterprise: versions 16.0.1 up to the fixed build listed at aka.ms/OfficeSecurityReleases
- Office 365 for Mac: versions 1.0.0 to below 16.114.26101123 (unverified)
- Office LTSC 2021 (Windows): versions 16.0.1 to below 16.0.14334.20974
- Office LTSC 2024 (Windows): versions 16.0.0 to below 16.0.17932.21056
- Office LTSC for Mac 2021 and 2024: versions below 16.114.26101123
- Office Online Server: versions 16.0.0.0 to below 16.0.10417.20228
Fixed in
- Office LTSC 2021 (Windows): 16.0.14334.20974 or later
- Office LTSC 2024 (Windows): 16.0.17932.21056 or later
- Office Online Server: 16.0.10417.20228 or later (KB5002928)
- Microsoft 365 Apps for Enterprise: Unknown. Check aka.ms/OfficeSecurityReleases.
- Office for Mac: 16.114.26101123 according to one source, not yet verified. Check the MSRC page.
Workaround
Unknown. No vendor-documented workaround was found; patching is the only fix described in the sources.
Exploitation
- Not listed in CISA KEV.
- CISA SSVC: exploitation none, automatable no.
- Microsoft rates exploit code maturity as Unproven.
- No public proof of concept found.
- No source links this CVE to in-the-wild exploitation.
Our recommendation
- Patch Microsoft 365 Apps, Office LTSC and Office for Mac on all endpoints as part of the October 2026 update cycle.
- Prioritise Office Online Server instances, especially internet-facing ones, and patch them first.
- Verify the exact fixed build numbers on the MSRC page before rollout.
- Keep Protected View and restrictions on Enable Editing for files from the internet or email.
- Restrict or block Excel macros and untrusted attachments where possible.
- Monitor CISA KEV and the MSRC page for changes in exploitation status.
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 Response Center: CVE-2026-97747 msrc.microsoft.com
- OpenCVE: CVE-2026-97747 app.opencve.io
- Vulners: CVE-2026-97747 vulners.com
- Microsoft Support: Office Online Server KB5002928 support.microsoft.com
- Microsoft 365 Apps security updates learn.microsoft.com
- Release notes for Office for Mac learn.microsoft.com
- Strix: CVE-2026-97747 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 31 Oct 2026, 17:35.
Original description (NVD)
Use after free 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.
Affected? We can help.
We check whether your systems are affected, install updates and close the gap – continuously with the System Health Checker if you wish.