# CVE-2026-118726: Microsoft Office Excel heap-based buffer overflow

Source: https://junglewise.ai/threats/cve-2026-118726-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-2026-118726 · Severity: high · CVSS 8.8 · Published 2026-11-10

Microsoft Office Excel, a widely-used spreadsheet application for business data analysis and reporting, contains a heap-based buffer overflow vulnerability. An attacker can exploit this flaw remotely to execute arbitrary code on a user's computer, potentially leading to data theft, system compromise, or further attacks on corporate networks.

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

## Quick answers

**Is CVE-2026-118726 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-118726 being exploited in the wild.

**How severe is CVE-2026-118726?** 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-2026-118726?** 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-2026-118726 attacked?** It is attacked over the network.

**Am I affected by CVE-2026-118726?** 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 in Microsoft Office Excel allows remote code execution when processing specially crafted Excel files. The vulnerability can be exploited over the network without authentication or user interaction beyond opening a malicious file, giving an attacker complete system control on the affected machine.

## Affected products

- Microsoft Office Excel

## Timeline

- 2026-11-10: disclosed

## References

- [https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-118726](https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-118726)

## 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)