CVE-2026-120788: Microsoft Office Excel heap-based buffer overflow

CVE-2026-120788 · Severity: high · CVSS 8.8 · Published 2026-11-10

Microsoft Excel, a spreadsheet application used across organizations for financial analysis and data management, contains a heap buffer overflow vulnerability that could allow an attacker to execute malicious code on a user's computer through a specially crafted Excel file. If exploited, an attacker could gain full control of the affected system, potentially leading to data theft, system compromise, or further network penetration.

Technologies: Microsoft Office Excel. Vendors: Microsoft.

Quick answers

Is CVE-2026-120788 exploited in the wild?
No. Junglewise Threat Intelligence has no report of CVE-2026-120788 being exploited in the wild.
How severe is CVE-2026-120788?
High severity, with a CVSS score of 8.8, published 10 November 2026.
Which products and versions are affected?
Microsoft Office Excel.
Is there a fix for CVE-2026-120788?
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-2026-120788 attacked?
It is attacked over the network, in a web application.
Am I affected by CVE-2026-120788?
Check whether you run Microsoft Office Excel. 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 remote code execution via a network attack vector. The vulnerability requires user interaction (opening a malicious Excel file) but does not require authentication. Successful exploitation grants the attacker code execution in the context of the Excel process.

Affected products

  • Microsoft Office Excel

Timeline

  • 2026-11-10: disclosed

References

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