CVE-2026-55045: Microsoft Office out-of-bounds read code execution

CVE-2026-55045 · Severity: high · CVSS 8.4 · Published 2026-07-14

A vulnerability in Microsoft Office and SharePoint Server could allow an attacker to execute malicious code on a user's computer. Microsoft Office is a widely used suite of productivity tools, and SharePoint is a platform for document management and collaboration. If exploited, this flaw could allow an unauthorized person to gain control over a system, potentially leading to data theft or further network compromise.

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 SharePoint Enterprise Server 2016. Vendors: Microsoft.

Quick answers

Is CVE-2026-55045 exploited in the wild?
No. Junglewise Threat Intelligence has no report of CVE-2026-55045 being exploited in the wild.
How severe is CVE-2026-55045?
High severity, with a CVSS score of 8.4, published 14 July 2026.
Which products and versions are affected?
Microsoft 365 Apps for Enterprise 16.0.1 and later versions prior to security updates; Microsoft Office 2016 16.0.0 to 16.0.5561.1000; Microsoft Office 2019 19.0.0 and later versions prior to security updates; Microsoft Office 365 for Mac 1.0.0 to 16.111.26071215; and 3 more.
Is there a fix for CVE-2026-55045?
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-2026-55045 attacked?
It is attacked with local access, in a network appliance.
Am I affected by CVE-2026-55045?
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 improperly handles memory during the processing of specific data, allowing an attacker to read beyond the intended buffer. This memory corruption can be leveraged to achieve local code execution. The attack vector is local, meaning an attacker would typically need to convince a user to open a specially crafted file or have existing access to the system. Affected products include Office 2016, 2019, LTSC versions, and SharePoint Server 2016/2019. Microsoft has released security updates to address this issue.

Affected products

  • Microsoft Microsoft 365 Apps for Enterprise 16.0.1 and later versions prior to security updates
  • Microsoft Microsoft Office 2016 16.0.0 to 16.0.5561.1000
  • Microsoft Microsoft Office 2019 19.0.0 and later versions prior to security updates
  • Microsoft Microsoft Office 365 for Mac 1.0.0 to 16.111.26071215
  • Microsoft Microsoft Office LTSC 2021 16.0.1 and later versions prior to security updates
  • Microsoft Microsoft Office LTSC 2024 16.0.0 and later versions prior to security updates
  • Microsoft Microsoft SharePoint Enterprise Server 2016 16.0.0 to 16.0.5561.1001

Timeline

  • 2026-07-14: disclosed: Vulnerability published by Microsoft and NVD.
  • 2026-07-14: advisory: Microsoft released security update guide.

References

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