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

Source: https://junglewise.ai/threats/cve-2026-120788-heap-based-buffer-overflow-in-microsoft-office-excel-allows-an  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-11-10. Updated: 2026-11-10  
License: CC BY 4.0 with a link back

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](https://junglewise.ai/threats/technologies/office-excel). Vendors: [Microsoft](https://junglewise.ai/threats/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

- [https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-120788](https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-120788)

## Related threats

- [Microsoft Office Excel unsafe deserialization in file parsing](https://junglewise.ai/threats/cve-2026-124229-deserialization-of-untrusted-data-in-microsoft-office-excel)
- [Microsoft Office Excel use-after-free remote code execution](https://junglewise.ai/threats/cve-2026-124187-use-after-free-in-microsoft-office-excel-allows-an-unauthorized)
- [Microsoft Office Excel buffer over-read information disclosure](https://junglewise.ai/threats/cve-2026-124183-buffer-over-read-in-microsoft-office-excel-allows-an)
- [Microsoft Office Excel out-of-bounds read information disclosure](https://junglewise.ai/threats/cve-2026-124179-out-of-bounds-read-in-microsoft-office-excel-allows-an)
- [Microsoft Office Excel out-of-bounds read](https://junglewise.ai/threats/cve-2026-124178-out-of-bounds-read-in-microsoft-office-excel-allows-an)