Microsoft Office Excel: Out-of-bounds read leads to information disclosure
Summary
A out-of-bounds read in Microsoft Office Excel allows an unauthorized attacker to disclose information over a network. The attack requires a user to interact with a crafted Excel file, for example one opened from an email attachment or a download. The flaw does not allow code execution or changes to data or availability.
Affected
- Microsoft 365 Apps for Enterprise: 16.0.1 before the build listed at https://aka.ms/OfficeSecurityReleases
- Office 365 for Mac: 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
- 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
Fixed in
- Office LTSC 2021: 16.0.14334.21048
- Office LTSC 2024: 16.0.17932.21140
- Office 365 and LTSC for Mac: 16.115.26110837
- Office Online Server: 16.0.10417.20236
- Microsoft 365 Apps for Enterprise: fixed build unknown, verify at https://aka.ms/OfficeSecurityReleases
Workaround
Unknown. No workaround is documented in the sources reviewed. Rely on patching.
Exploitation
- No known exploitation in the wild at the time of analysis.
- No public proof of concept found.
- CISA SSVC: exploitation none, not automatable.
- CVE record temporal metrics: exploit code maturity unproven.
Our recommendation
- Patch Microsoft 365 Apps, Office LTSC and Office Online Server to the fixed builds in the normal monthly update cycle.
- Patch earlier if Excel files from external parties are processed routinely.
- Keep Protected View enabled and restrict macros.
- Block or sandbox Office files from email and internet downloads where possible.
- Monitor for exploitation reports and check the NVD record for updates.
Information from Microsoft (Patch Tuesday November 2026)
- Severity (Microsoft)
- Important
- Impact
- Information disclosure – 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: CVE-2026-124179 msrc.microsoft.com
- CVE Record CVE-2026-124179 www.cve.org
- Microsoft 365 Apps security updates learn.microsoft.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, 12:02.
Original description (NVD)
Out-of-bounds read in Microsoft Office Excel allows an unauthorized attacker to disclose information 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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