# CVE-2026-118714: Microsoft Excel heap-based buffer overflow in spreadsheet parsing

Source: https://junglewise.ai/threats/cve-2026-118714-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-2026-118714 · Severity: high · CVSS 8.8 · Published 2026-11-10

Microsoft Excel, a widely used spreadsheet application, contains a heap-based buffer overflow vulnerability in its parsing logic. An attacker could exploit this flaw by sending a specially crafted spreadsheet file over a network to execute arbitrary code on the victim's machine. Successful exploitation could lead to complete system compromise, data theft, or deployment of malware.

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

## Quick answers

**Is CVE-2026-118714 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-118714 being exploited in the wild.

**How severe is CVE-2026-118714?** High severity, with a CVSS score of 8.8, published 10 November 2026.

**Which products and versions are affected?** Microsoft Excel.

**Is there a fix for CVE-2026-118714?** 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-2026-118714 attacked?** It is attacked over the network, in a software library.

**Am I affected by CVE-2026-118714?** Check whether you run Microsoft 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 Excel's spreadsheet file parsing code. The vulnerability is triggered when processing malformed spreadsheet files and allows network-based code execution without requiring user authentication or special privileges. An attacker can craft a malicious Excel file that, when opened or processed by a vulnerable version, overwrites heap memory and achieves arbitrary code execution.

## Affected products

- Microsoft Excel

## References

- [https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-118714](https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-118714)

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