# CVE-2026-55025: Microsoft Excel type confusion code execution

Source: https://junglewise.ai/threats/cve-2026-55025-microsoft-excel-type-confusion-code-execution  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-07-14. Updated: 2026-07-14  
License: CC BY 4.0 with a link back

CVE-2026-55025 · Severity: high · CVSS 7.8 · Published 2026-07-14

Microsoft Excel is a widely used spreadsheet application for data analysis and reporting. A security vulnerability has been identified that could allow an attacker to run malicious code on a user's computer if the user is tricked into opening a specially crafted Excel file. This could lead to a full compromise of the user's workstation, including the theft of sensitive data or the installation of malware.

Technologies: [Microsoft 365 Apps for Enterprise](https://junglewise.ai/threats/technologies/365-apps-for-enterprise), [Microsoft Excel 2016](https://junglewise.ai/threats/technologies/excel-2016), [Microsoft Office 2019](https://junglewise.ai/threats/technologies/office-2019), [Microsoft Office 365 for Mac](https://junglewise.ai/threats/technologies/office-365-for-mac), [Microsoft Office LTSC 2021](https://junglewise.ai/threats/technologies/office-ltsc-2021), [Microsoft Office LTSC 2024](https://junglewise.ai/threats/technologies/office-ltsc-2024), [Microsoft Office Online Server](https://junglewise.ai/threats/technologies/office-online-server). Vendors: [Microsoft](https://junglewise.ai/threats/vendors/microsoft).

## Quick answers

**Is CVE-2026-55025 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-55025 being exploited in the wild.

**How severe is CVE-2026-55025?** High severity, with a CVSS score of 7.8, published 14 July 2026.

**Which products and versions are affected?** Microsoft 365 Apps for Enterprise versions prior to July 2026 updates; Microsoft Excel 2016 versions prior to 16.0.5561.1001; Microsoft Office 2019 versions prior to July 2026 updates; Microsoft Office 365 for Mac versions prior to 16.111.26071215; and 3 more.

**Is there a fix for CVE-2026-55025?** 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-2026-55025 attacked?** It is attacked with local access, in a network appliance.

**Am I affected by CVE-2026-55025?** Check whether you run Microsoft 365 Apps for Enterprise, Microsoft Excel 2016, Microsoft Office 2019 or one of the others listed at an affected version. 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 type confusion vulnerability (CWE-843) exists in Microsoft Office Excel due to the application accessing resources using an incompatible type. The vulnerability is triggered when a user opens a maliciously crafted Excel file. While the attack vector is classified as local, it requires user interaction (UI:R) to execute. Successful exploitation allows an attacker to achieve arbitrary code execution in the context of the current user. Microsoft has released security updates to address this issue across various versions of Office, including Microsoft 365 Apps, Office LTSC, and Office Online Server.

## Affected products

- Microsoft Microsoft 365 Apps for Enterprise versions prior to July 2026 updates
- Microsoft Microsoft Excel 2016 versions prior to 16.0.5561.1001
- Microsoft Microsoft Office 2019 versions prior to July 2026 updates
- Microsoft Microsoft Office 365 for Mac versions prior to 16.111.26071215
- Microsoft Microsoft Office LTSC 2021 versions prior to July 2026 updates
- Microsoft Microsoft Office LTSC 2024 versions prior to July 2026 updates
- Microsoft Office Online Server versions prior to 16.0.10417.20175

## Timeline

- 2026-07-14: disclosed
- 2026-07-14: advisory

## References

- [https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-55025](https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-55025)

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