Microsoft Office Excel: Use-after-free leading to remote code execution
Summary
A use-after-free flaw (CWE-416) in Microsoft Office Excel allows an unauthorized attacker to execute code over a network. Exploitation requires a user to open a crafted file, for example one received by email or downloaded from the internet. The CVSS base score is 8.8 (High).
Affected
- Microsoft 365 Apps for Enterprise: 16.0.1 before the fixed build (build number unknown, see MSRC)
- Office 365 for Mac: 1.0.0 before 16.115.26110837
- Office LTSC 2021: 16.0.1 before 16.0.14334.21048
- Office LTSC 2024: 16.0.0 before 16.0.17932.21140 (third-party source, unverified)
- Office LTSC for Mac 2021: 16.0.1 before 16.115.26110837
- Office LTSC for Mac 2024: 16.0.0 before 16.115.26110837
- Office Online Server: 16.0.0.0 before 16.0.10417.20236
- SharePoint: unconfirmed, check MSRC
Fixed in
- Office 365 for Mac: 16.115.26110837
- Office LTSC 2021: 16.0.14334.21048
- Office LTSC for Mac 2021 and 2024: 16.115.26110837
- Office LTSC 2024: 16.0.17932.21140 (unverified)
- Office Online Server: 16.0.10417.20236
- Microsoft 365 Apps for Enterprise: Unknown (see the Microsoft release page)
Workaround
- Unknown. No vendor workaround identified.
- Until patched: do not open untrusted spreadsheets from email or downloads (general hardening guidance, not confirmed by a source for this CVE).
Exploitation
- Not known to be exploited in the wild. CISA SSVC lists exploitation as none.
- No public proof of concept found.
- The CVSS temporal vector includes E:U (unproven exploit code maturity).
- CISA KEV listing not verified.
Our recommendation
- Deploy the November 2026 Microsoft security updates on all systems with Excel as a priority, especially where staff open invoices or spreadsheets from outside the company.
- Verify the installed build number on each endpoint against the MSRC advisory.
- Check the MSRC advisory for SharePoint impact and any interim guidance.
- Remind staff not to open unexpected spreadsheets from email or downloads, and monitor for suspicious Excel activity.
Information from Microsoft (Patch Tuesday November 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)
- KB5002946
Public exploits
PoC-in-GitHub, Metasploit and Exploit-DB list nothing for this CVE.
Research sources
- CVE.org CNA record www.cve.org
- MSRC Security Update Guide msrc.microsoft.com
- Strix aggregator entry www.strix.ai
- Threat intel mirror cve.threatint.com
- Patch Tuesday coverage, November 2026 cybersecuritynews.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 10 Nov 2026, 21:41.
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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