CVE-2026-55027: Microsoft Office out-of-bounds read information disclosure

CVE-2026-55027 · Severity: medium · CVSS 5.5 · Published 2026-07-14

A security vulnerability has been identified in Microsoft Office and SharePoint products that could allow an attacker to access sensitive information. To exploit this, an attacker would typically need to convince a user to open a specially crafted file on their computer. While this does not allow for direct control of the system, it could lead to the unauthorized disclosure of private data stored in the computer's memory.

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-2026-55027 exploited in the wild?
No. Junglewise Threat Intelligence has no report of CVE-2026-55027 being exploited in the wild.
How severe is CVE-2026-55027?
Medium severity, with a CVSS score of 5.5, published 14 July 2026.
Which products and versions are affected?
Microsoft 365 Apps for Enterprise 16.0.1 to latest security release; Microsoft Office 2016 16.0.0 to 16.0.5561.1000; Microsoft Office 2019 19.0.0 to latest security release; Microsoft Office 365 for Mac 1.0.0 to 16.111.26071215; and 6 more.
Is there a fix for CVE-2026-55027?
A patch was published on 2026-07-14: Security updates released by Microsoft Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
How is CVE-2026-55027 attacked?
It is attacked with local access, in a network appliance.
Am I affected by CVE-2026-55027?
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 out-of-bounds read vulnerability (CWE-125) exists in multiple versions of Microsoft Office and SharePoint Server. The flaw is triggered when the application fails to properly validate input, allowing a local attacker to read data beyond the intended buffer. Exploitation requires user interaction, such as opening a malicious file. Successful exploitation results in information disclosure, potentially exposing sensitive memory contents to the attacker. Microsoft has addressed this through security updates across the affected product lines.

Affected products

  • Microsoft Microsoft 365 Apps for Enterprise 16.0.1 to latest security release
  • Microsoft Microsoft Office 2016 16.0.0 to 16.0.5561.1000
  • Microsoft Microsoft Office 2019 19.0.0 to latest security release
  • Microsoft Microsoft Office 365 for Mac 1.0.0 to 16.111.26071215
  • Microsoft Microsoft Office LTSC 2021 16.0.1 to latest security release
  • Microsoft Microsoft Office LTSC 2024 16.0.0 to latest security release
  • Microsoft Microsoft Office LTSC for Mac 2021 16.0.1 to 16.111.26071215
  • Microsoft Microsoft Office LTSC for Mac 2024 16.0.0 to 16.111.26071215
  • Microsoft Microsoft SharePoint Enterprise Server 2016 16.0.0 to 16.0.5561.1001
  • Microsoft Microsoft SharePoint Server 2019 16.0.0 to latest security release

Timeline

  • 2026-07-14: advisory: Initial publication by Microsoft and NVD
  • 2026-07-14: patched: Security updates released by Microsoft

References

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