CVE-2026-55125: Microsoft Office heap overflow in code execution

CVE-2026-55125 · Severity: high · CVSS 7.8 · Published 2026-07-14

A security vulnerability exists in Microsoft Office and SharePoint that could allow an attacker to run malicious code on a user's computer. To exploit this, an attacker would typically need to trick a user into opening a specially crafted file. If successful, the attacker could gain the same permissions as the local user, potentially leading to data theft or full system 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-2026-55125 exploited in the wild?
No. Junglewise Threat Intelligence has no report of CVE-2026-55125 being exploited in the wild.
How severe is CVE-2026-55125?
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 Office 2016 < 16.0.5561.1000; Microsoft Office 2019 All versions; Microsoft Office 365 for Mac < 16.111.26071215; and 3 more.
Is there a fix for CVE-2026-55125?
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-2026-55125 attacked?
It is attacked with local access, in a network appliance.
Am I affected by CVE-2026-55125?
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

A heap-based buffer overflow (CWE-122) exists in multiple Microsoft Office products and SharePoint Server. The vulnerability is triggered when the application fails to properly validate input while processing a crafted file, leading to memory corruption. An attacker can exploit this by convincing a user to open a malicious document, resulting in arbitrary code execution in the context of the current user. The attack vector is local with a requirement for user interaction (UI:R). Microsoft has released security updates to address this issue across affected versions of Office 2016, 2019, LTSC, and Microsoft 365.

Affected products

  • Microsoft Office 2016 < 16.0.5561.1000
  • 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 SharePoint Enterprise Server 2016 < 16.0.5561.1001

Timeline

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

References

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