Microsoft Office Excel: Heap-based buffer overflow allows code execution
Summary
A heap-based buffer overflow in Microsoft Office Excel allows an unauthorized attacker to execute code over a network. Exploitation requires that a user opens a crafted file, for example one received by email or downloaded from the internet. The CVE is rated CVSS 8.8, was published on 2026-11-10, and NVD analysis is still pending.
Affected
- Microsoft 365 Apps for Enterprise: 16.0.1 up to the fixed build (build not stated in the CVE record)
- Microsoft Office 365 for Mac: 1.0.0 before 16.115.26110837
- Microsoft Office LTSC 2021: 16.0.1 before 16.0.14334.21048
- Microsoft Office LTSC 2024: 16.0.0 before 16.0.17932.21140
- Microsoft Office LTSC for Mac 2021: 16.0.1 before 16.115.26110837
- Microsoft Office LTSC for Mac 2024: 16.0.0 before 16.115.26110837
- Microsoft Office Online Server: 16.0.0.0 before 16.0.10417.20236
Version data comes from the CVE record and third-party mirrors and is not yet verified against the MSRC advisory.
Fixed in
- Microsoft Office LTSC 2021: 16.0.14334.21048
- Microsoft Office LTSC 2024: 16.0.17932.21140
- Microsoft Office 365 for Mac and LTSC for Mac: 16.115.26110837
- Microsoft Office Online Server: 16.0.10417.20236
- Microsoft 365 Apps for Enterprise: Unknown (build not stated)
Workaround
Unknown. No vendor-specific workaround has been identified. Apply the vendor update and check the MSRC advisory for interim guidance.
Exploitation
- No in-the-wild exploitation or public proof of concept has been reported at the time of writing.
- The CISA SSVC assessment lists exploitation as none and automatable as no.
- CISA KEV and NVD analysis status could not be verified.
Our recommendation
- Patch affected Office installations in the next Patch Tuesday cycle at the latest, and prioritise users who receive external files.
- Verify the exact fixed builds in the MSRC advisory before rollout.
- Keep Protected View enabled for files from the internet and email, and limit macro use.
- Monitor for exploitation and recheck the status in one to two weeks.
Information from Microsoft (Patch Tuesday November 2026)
- Severity (Microsoft)
- Critical
- 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 Response Center: CVE-2026-118297 msrc.microsoft.com
- CVE Record CVE-2026-118297 www.cve.org
- Strix AI: CVE-2026-118297 www.strix.ai
- Threatint: CVE-2026-118297 cve.threatint.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, 22:03.
Original description (NVD)
Heap-based buffer overflow 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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