Microsoft Excel: Remote code execution via use-after-free
Summary
A use-after-free flaw (CWE-416) in Microsoft Excel, part of Microsoft 365 Apps and Office LTSC editions, allows remote code execution. An unauthenticated attacker can run code on the victim's system over the network. Exploitation requires the victim to open a crafted Excel file, for example one received by email or downloaded from the internet.
Affected
- Microsoft 365 Apps for Enterprise (Windows): 16.0.1 up to the build named in the MSRC advisory
- Microsoft Office LTSC 2021 (Windows): 16.0.1 to before 16.0.14334.20974
- Microsoft Office LTSC 2024 (Windows): 16.0.0 to before 16.0.17932.21056
- Microsoft 365 Apps and Office 365 for Mac: 1.0.0 to before 16.114.26101123
- Microsoft Office LTSC for Mac 2021 and 2024: before 16.114.26101123
- Microsoft Office Online Server: 16.0.0.0 to before 16.0.10417.20228
Fixed in
- Microsoft 365 Apps (Windows): latest build of the October 2026 security update
- Office LTSC 2021 (Windows): 16.0.14334.20974 or later
- Office LTSC 2024 (Windows): 16.0.17932.21056 or later
- Office for Mac and Office LTSC for Mac: 16.114.26101123 or later
- Office Online Server: 16.0.10417.20228 or later (per Microsoft KB5002928)
The fixed builds for LTSC and Mac are taken from the CVE record. Verify all build numbers on the MSRC advisory before rollout.
Workaround
Unknown. Microsoft documents no workaround; applying the security update is the stated remedy.
Exploitation
- No evidence of exploitation in the wild found at the time of writing.
- CISA SSVC data: exploitation none, automatable no.
- KEV listing: not listed according to a third-party tracker; not verified against the CISA catalogue.
- No public proof of concept found.
Our recommendation
- Install the October 2026 security updates for Microsoft 365 Apps, Office LTSC and Office Online Server as a priority.
- Check whether Office Online Server is deployed and internet-facing, and patch it first if so.
- Keep Protected View enabled and block or sandbox Excel files from unknown internet and email sources until patched.
- Verify installed builds on the MSRC advisory and monitor for signs of exploitation.
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-2026-97010 msrc.microsoft.com
- Microsoft KB5002928: Office Online Server security update support.microsoft.com
- Microsoft 365 Apps security updates learn.microsoft.com
- Release notes for Office for Mac learn.microsoft.com
- OpenCVE: CVE-2026-97010 app.opencve.io
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, 17:44.
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.
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