CVE-2026-100210: Microsoft Office Excel heap-based buffer overflow

CVE-2026-100210 · Severity: high · CVSS 8.8 · Published 2026-10-13

Microsoft Office Excel contains a heap-based buffer overflow vulnerability that could allow an attacker to execute arbitrary code on a user's computer through the network. An attacker could exploit this by sending a specially crafted Excel file, potentially gaining full control of the affected system to steal data, install malware, or disrupt operations.

Technologies: Microsoft 365 Apps, Microsoft 365, Microsoft Office 2021, Microsoft Office 2024, Microsoft Office Excel, Microsoft Office Online Server. Vendors: Microsoft.

Quick answers

Is CVE-2026-100210 exploited in the wild?
No. Junglewise Threat Intelligence has no report of CVE-2026-100210 being exploited in the wild.
How severe is CVE-2026-100210?
High severity, with a CVSS score of 8.8, published 13 October 2026.
Which products and versions are affected?
Microsoft Office Excel.
Is there a fix for CVE-2026-100210?
No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.
How is CVE-2026-100210 attacked?
It is attacked over the network.
Am I affected by CVE-2026-100210?
Check whether you run Microsoft 365 Apps, Microsoft 365, Microsoft Office 2021 or one of the others listed. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

Technical details

A heap-based buffer overflow exists in Microsoft Office Excel's file parsing logic, allowing an attacker to write data beyond allocated heap memory boundaries. The vulnerability can be triggered via network delivery of a malicious Excel file without requiring user authentication, though user interaction (opening the file) is needed. Successful exploitation leads to remote code execution with the privileges of the user running Excel.

Affected products

  • Microsoft Office Excel

Timeline

  • 2026-10-13: disclosed

References

This page as Markdown. Free to reuse under CC BY 4.0 with a link back.