# CVE-2026-120790: Microsoft Office Excel heap-based buffer overflow

Source: https://junglewise.ai/threats/cve-2026-120790-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-2026-120790 · Severity: high · CVSS 8.8 · Published 2026-11-10

Microsoft Office Excel, a spreadsheet application used for data analysis and financial reporting, contains a heap-based buffer overflow vulnerability that allows an attacker to execute arbitrary code on a user's computer. An attacker can exploit this flaw by sending a specially crafted spreadsheet file over the network, potentially leading to unauthorized access, data theft, or system compromise.

Technologies: [Microsoft Office Excel](https://junglewise.ai/threats/technologies/office-excel). Vendors: [Microsoft](https://junglewise.ai/threats/vendors/microsoft).

## Quick answers

**Is CVE-2026-120790 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-120790 being exploited in the wild.

**How severe is CVE-2026-120790?** 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-2026-120790?** 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-2026-120790 attacked?** It is attacked over the network, in a web application.

**Am I affected by CVE-2026-120790?** 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 vulnerability exists in Microsoft Office Excel's spreadsheet processing engine that fails to properly validate input data before writing to heap memory. The vulnerability is triggered when Excel processes a malicious spreadsheet file sent over the network, requiring user interaction to open the file. Successful exploitation allows arbitrary code execution in the context of the user running Excel.

## Affected products

- Microsoft Office Excel

## Timeline

- 2026-11-10: disclosed

## References

- [https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-120790](https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-120790)

## 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)
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- [Microsoft Office Excel out-of-bounds read](https://junglewise.ai/threats/cve-2026-124178-out-of-bounds-read-in-microsoft-office-excel-allows-an)