Microsoft Office Excel: Remote code execution via use-after-free
Summary
A use-after-free flaw (CWE-416) in Microsoft Office Excel allows an unauthorized attacker to execute code over a network. The attack requires that a user opens a crafted spreadsheet or link, so user interaction is needed. Successful exploitation can lead to full compromise of confidentiality, integrity and availability with the privileges of the user running Excel.
Affected
- Microsoft 365 Apps for Enterprise: 16.0.1 before the build listed at https://aka.ms/OfficeSecurityReleases (fixed build number unknown)
- Microsoft Office 365 for Mac and LTSC for Mac 2021: 16.0.1 / 1.0.0 before 16.114.26101123
- Microsoft Office LTSC for Mac 2024: before 16.114.26101123 (listed in one source only)
- Microsoft Office LTSC 2021: 16.0.1 before 16.0.14334.20974
- Microsoft Office LTSC 2024: 16.0.0 before 16.0.17932.21056
- Office Online Server: 16.0.0.0 before 16.0.10417.20228
Fixed in
- Microsoft 365 Apps for Enterprise: Unknown (see https://aka.ms/OfficeSecurityReleases)
- Microsoft Office 365 for Mac and LTSC for Mac 2021: 16.114.26101123
- Microsoft Office LTSC 2021: 16.0.14334.20974
- Microsoft Office LTSC 2024: 16.0.17932.21056
- Office Online Server: 16.0.10417.20228
Workaround
No vendor-confirmed workaround known. The security update is the stated remediation. Check the MSRC advisory for any official mitigation.
Exploitation
- CISA KEV: not listed
- CISA SSVC: exploitation none, automatable no, technical impact total
- No public proof of concept found; one secondary source reports no confirmed public exploit code (low confidence)
- EPSS: not yet available
Our recommendation
- Patch Office desktop applications (including Mac clients) to the fixed builds in the next regular update cycle, with high priority
- Confirm exact fixed builds for Microsoft 365 Apps on the MSRC advisory page
- Check whether Office Online Server is deployed and published to the internet, and patch it if so
- Until patched, restrict opening untrusted spreadsheets from email and downloads, and keep Protected View enabled
- Recheck CISA KEV and exploitation status regularly
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
- MSRC Security Update Guide msrc.microsoft.com
- OpenCVE app.opencve.io
- Vulners CISA Vulnrichment vulners.com
- Strix AI www.strix.ai
- threatint CVE record cve.threatint.com
- OffSeq Radar radar.offseq.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, 16:15.
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.