# CVE-2026-55024: Microsoft Excel type confusion code execution

Source: https://junglewise.ai/threats/cve-2026-55024-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-2026-55024 · Severity: high · CVSS 7.8 · Published 2026-07-14

Microsoft Excel, a widely used spreadsheet application, contains a security flaw that could allow an attacker to take control of a user's computer. To exploit this, an attacker would typically need to trick a user into opening a specially crafted malicious file. If successful, the attacker could run unauthorized software, access sensitive data, or disrupt business operations on the affected machine.

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-2026-55024 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-55024 being exploited in the wild.

**How severe is CVE-2026-55024?** High severity, with a CVSS score of 7.8, published 14 July 2026.

**Which products and versions are affected?** Microsoft 365 Apps for Enterprise All versions; Microsoft Excel 2016 < 16.0.5561.1001; Microsoft Office 2019 All versions; Microsoft Office 365 for Mac < 16.111.26071215; and 3 more.

**Is there a fix for CVE-2026-55024?** 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-2026-55024 attacked?** It is attacked with local access, in a network appliance.

**Am I affected by CVE-2026-55024?** 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 the application processes a specially crafted file, leading to memory corruption. An attacker can exploit this by convincing a user to open a malicious Excel document, resulting in arbitrary code execution in the context of the current user. The attack vector is local, but requires user interaction (UI:R). Microsoft has released security updates to address this issue across various versions of Office, including Office 2016, 2019, LTSC, and Microsoft 365 Apps.

## Affected products

- Microsoft Excel 2016 < 16.0.5561.1001
- Microsoft Office 2019 All versions
- Microsoft Office LTSC 2021 All versions
- Microsoft Office LTSC 2024 All versions
- Microsoft 365 Apps for Enterprise All versions
- Microsoft Office 365 for Mac < 16.111.26071215
- Microsoft Office Online Server < 16.0.10417.20175

## Timeline

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

## References

- [https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-55024](https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-55024)

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