Microsoft Office Excel: Remote code execution via uninitialized resource
Summary
A use of an uninitialized resource in Microsoft Office Excel allows an unauthorized attacker to execute code over a network. The attack requires a user to interact, for example by opening a crafted file, and the CVSS vector rates the attack complexity as high. Exploit code is not known at publication, and the exact trigger is not yet confirmed.
Affected
- Microsoft 365 Apps for Enterprise: 16.0.1 to before the fixed build (not stated in the CVE record)
- Office 365 for Mac: 1.0.0 to before 16.115.26110837
- Office LTSC 2021: 16.0.1 to before 16.0.14334.21048 (EUVD lists 16.0.14334.20974, conflict unresolved)
- Office LTSC 2024: 16.0.0 to before 16.0.17932.21140 (EUVD lists 16.0.17932.21056, conflict unresolved)
- Office LTSC for Mac 2021 and 2024: 16.0.0 to before 16.115.26110837 (unverified)
- Office Online Server: 16.0.0.0 to before 16.0.10417.20236
Fixed in
- Office Online Server: fix included in KB 5002946 (per SharePoint blog)
- Other products: Unknown. Check the MSRC advisory for fixed build numbers.
Workaround
Unknown. No workaround is documented in the sources reviewed.
Exploitation
- Not confirmed for this CVE.
- CVSS temporal vector E:U (exploit code maturity unproven) indicates no known exploit code at publication.
- No public proof of concept found.
- CISA SSVC: exploitation none, automatable no, technical impact total.
Our recommendation
- Install the November 2026 Office security updates on all Microsoft 365 Apps, Office LTSC and Office for Mac clients, and confirm the fixed build against the MSRC advisory.
- Check whether Office Online Server is in use and apply KB 5002946 if so.
- Block or sandbox macros and files from untrusted sources, and warn users not to open unexpected spreadsheets from email or links.
- Monitor the MSRC advisory for updates on exploitation status.
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
- Microsoft Security Update Guide (MSRC) msrc.microsoft.com
- CVE Record (CVE Program) www.cve.org
- EUVD record (Vulners) vulners.com
- Strix.ai CVE page www.strix.ai
- SharePoint security fixes November 2026 (Stefan Gossner) blog.stefan-gossner.com
- Rapid7 Patch Tuesday November 2026 www.rapid7.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 11 Nov 2026, 05:35.
Original description (NVD)
Use of uninitialized resource 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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