CVE-2026-55026: Microsoft Office integer overflow information disclosure

CVE-2026-55026 · Severity: medium · CVSS 6.2 · Published 2026-07-14

A vulnerability in Microsoft Office and SharePoint could allow an unauthorized person with local access to a computer to view sensitive information. This issue affects various versions of the productivity suite, including Office 2016, 2019, and Microsoft 365 Apps. While the attacker must have local access to the system, a successful exploit could lead to the unauthorized disclosure of data stored or processed by these applications.

Technologies: Microsoft 365 Apps for Enterprise, Microsoft Office 2016, Microsoft Office 2019, Microsoft Office 365 for Mac, Microsoft Office LTSC 2021, Microsoft Office LTSC 2024, Microsoft Office LTSC for Mac 2021, Microsoft Office LTSC for Mac 2024, Microsoft SharePoint Enterprise Server 2016, Microsoft SharePoint Server 2019. Vendors: Microsoft.

Quick answers

Is CVE-2026-55026 exploited in the wild?
No. Junglewise Threat Intelligence has no report of CVE-2026-55026 being exploited in the wild.
How severe is CVE-2026-55026?
Medium severity, with a CVSS score of 6.2, published 14 July 2026.
Which products and versions are affected?
Microsoft 365 Apps for Enterprise < 16.0.1; Microsoft Office 2016 < 16.0.5561.1000; Microsoft Office 2019 < 19.0.0; Microsoft Office 365 for Mac < 16.111.26071215; and 6 more.
Is there a fix for CVE-2026-55026?
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-2026-55026 attacked?
It is attacked with local access, in a network appliance.
Am I affected by CVE-2026-55026?
Check whether you run Microsoft 365 Apps for Enterprise, Microsoft Office 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

An integer overflow vulnerability (CWE-190) exists in Microsoft Office and SharePoint Server. The flaw is triggered when the application incorrectly handles specific numerical calculations, leading to a wraparound condition. An attacker with local access to the affected system can exploit this to bypass memory protections and disclose sensitive information from the process memory. The vulnerability affects multiple platforms including Windows (32-bit and x64) and macOS. Microsoft has released security updates to address this issue across the affected product lines.

Affected products

  • Microsoft Microsoft 365 Apps for Enterprise < 16.0.1
  • Microsoft Microsoft Office 2016 < 16.0.5561.1000
  • Microsoft Microsoft Office 2019 < 19.0.0
  • Microsoft Microsoft Office 365 for Mac < 16.111.26071215
  • Microsoft Microsoft Office LTSC 2021 < 16.0.1
  • Microsoft Microsoft Office LTSC 2024 < 16.0.0
  • Microsoft Microsoft Office LTSC for Mac 2021 < 16.111.26071215
  • Microsoft Microsoft Office LTSC for Mac 2024 < 16.111.26071215
  • Microsoft Microsoft SharePoint Enterprise Server 2016 < 16.0.5561.1001
  • Microsoft Microsoft SharePoint Server 2019 < 16.0.0

Timeline

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

References

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