Microsoft Office Excel: Use-after-free leading to remote code execution
Summary
Microsoft Office Excel contains a use-after-free vulnerability (CWE-416) that allows an unauthorized attacker to execute code over a network. Affected are Microsoft 365 Apps for Enterprise, Office LTSC 2021 and 2024, Office for Mac, Office LTSC for Mac 2021 and 2024, and Office Online Server. The attack requires that a user opens a crafted file (UI:R), but no privileges are needed (PR:N), so an external sender can trigger it. Microsoft rates the issue as Important, with a CVSS 3.1 base score of 8.8.
Affected
- Microsoft 365 Apps for Enterprise: 16.0.1 up to the fixed build listed on https://aka.ms/OfficeSecurityReleases
- 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 (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 (unverified)
Fixed in
- Office 365 for Mac and Office LTSC for Mac: 16.115.26110837
- Office LTSC 2021: 16.0.14334.21048
- Office LTSC 2024: 16.0.17932.21140 (unverified)
- Microsoft 365 Apps for Enterprise: fixed build not stated in the CVE record; see the Office security release page
- Office Online Server: 16.0.10417.20236 (unverified)
Workaround
Unknown.
Exploitation
- CISA SSVC: Exploitation none, Automatable no, Technical Impact total
- No evidence found that this CVE is exploited in the wild
- No public proof of concept found
Our recommendation
- Install the November 2026 Office security updates on all affected Office installations
- Confirm the fixed build numbers on the MSRC advisory and the Office security release page
- Check for separate updates on Office LTSC 2021/2024 and Office Online Server installations
- Until patched, treat Excel files from unknown senders with caution and keep Protected View enabled
- Monitor for exploitation reports and update priority if status changes
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.microsoft.com
- CVE.org CVE Record www.cve.org
- Microsoft Patch Tuesday coverage (BleepingComputer) www.bleepingcomputer.com
- Microsoft November 2026 Patch Tuesday (CyberSecurityNews) cybersecuritynews.com
- CVE threat intel summary cve.threatint.com
- Strix CVE-2026-118703 (aggregator, unverified versions) 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 10 Nov 2026, 22:02.
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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