# CVE-2026-55036: Microsoft Excel buffer over-read code execution

Source: https://junglewise.ai/threats/cve-2026-55036-microsoft-excel-buffer-over-read-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-2026-55036 · Severity: high · CVSS 7.8 · Published 2026-07-14

A security vulnerability has been identified in Microsoft Excel, the widely used spreadsheet application. If a user is tricked into opening a specially crafted malicious file, an attacker could gain the ability to run unauthorized code on the user's computer. This could lead to the theft of sensitive data, installation of malware, or full control over the affected workstation.

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 LTSC for Mac 2021](https://junglewise.ai/threats/technologies/office-ltsc-for-mac-2021), [Microsoft Office LTSC for Mac 2024](https://junglewise.ai/threats/technologies/office-ltsc-for-mac-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-2026-55036 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-55036 being exploited in the wild.

**How severe is CVE-2026-55036?** High severity, with a CVSS score of 7.8, published 14 July 2026.

**Which products and versions are affected?** Microsoft 365 Apps for Enterprise < 16.0.1; Microsoft Excel 2016 < 16.0.5561.1001; Microsoft Office 2019 All versions; Microsoft Office 365 for Mac < 16.111.26071215; and 5 more.

**Is there a fix for CVE-2026-55036?** 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-2026-55036 attacked?** It is attacked with local access, in a network appliance.

**Am I affected by CVE-2026-55036?** 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 buffer over-read vulnerability (CWE-126) exists in Microsoft Office Excel across multiple versions, including Office 2016, 2019, 2021, 2024, and Microsoft 365 Apps. The flaw is triggered when the application fails to properly validate input while reading from a memory buffer, which can be exploited via a specially crafted Excel file. While the attack vector is local, it requires user interaction (UI:R) to open the malicious document. Successful exploitation allows for arbitrary code execution in the context of the current user. Microsoft has released security updates to address this issue.

## Affected products

- Microsoft Microsoft 365 Apps for Enterprise < 16.0.1
- Microsoft Microsoft Excel 2016 < 16.0.5561.1001
- Microsoft Microsoft Office 2019 All versions
- Microsoft Microsoft Office 365 for Mac < 16.111.26071215
- Microsoft Microsoft Office LTSC 2021 All versions
- Microsoft Microsoft Office LTSC 2024 All versions
- Microsoft Microsoft Office LTSC for Mac 2021 < 16.111.26071215
- Microsoft Microsoft Office LTSC for Mac 2024 < 16.111.26071215
- Microsoft Office Online Server < 16.0.10417.20175

## Timeline

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

## References

- [https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-55036](https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-55036)

## Related threats

- [Microsoft Office Excel out-of-bounds read in parsing](https://junglewise.ai/threats/cve-2026-105718-out-of-bounds-read-in-microsoft-office-excel-allows-an)
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- [Microsoft Office out-of-bounds read information disclosure](https://junglewise.ai/threats/cve-2026-56195-microsoft-office-out-of-bounds-read-information-disclosure)