# CVE-2026-120791: Microsoft Office Excel heap-based buffer overflow

Source: https://junglewise.ai/threats/cve-2026-120791-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-2026-120791 · Severity: high · CVSS 8.8 · Published 2026-11-10

Microsoft Office Excel contains a heap-based buffer overflow vulnerability that allows an attacker to execute arbitrary code remotely. An attacker could exploit this by sending a specially crafted Excel file to a user, leading to complete system compromise and data theft. This affects users across all organization sizes that rely on Excel for spreadsheet processing.

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

## Quick answers

**Is CVE-2026-120791 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-120791 being exploited in the wild.

**How severe is CVE-2026-120791?** 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-2026-120791?** 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-2026-120791 attacked?** It is attacked over the network.

**Am I affected by CVE-2026-120791?** 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 parsing logic, reachable remotely via network delivery of a malicious Excel file. The vulnerability allows unauthenticated remote code execution with no user interaction required beyond opening a file. Exploitation results in arbitrary code execution with the privileges of the user running Excel.

## Affected products

- Microsoft Office Excel

## Timeline

- 2026-11-10: disclosed

## References

- [https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-120791](https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-120791)

## 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)