CVE-2026-55127: Microsoft Office Word heap overflow code execution

CVE-2026-55127 · Severity: high · CVSS 7.8 · Published 2026-07-14

A security vulnerability has been identified in Microsoft Office Word and related SharePoint services that could allow an attacker to take control of a user's computer. To exploit this, an attacker would typically need to trick a user into opening a specially crafted malicious file. If successful, the attacker could gain the same permissions as the local user, potentially leading to data theft, unauthorized software installation, or full system compromise.

Technologies: Microsoft SharePoint Server, Microsoft Word. Vendors: Microsoft.

Quick answers

Is CVE-2026-55127 exploited in the wild?
No. Junglewise Threat Intelligence has no report of CVE-2026-55127 being exploited in the wild.
How severe is CVE-2026-55127?
High severity, with a CVSS score of 7.8, published 14 July 2026.
Which products and versions are affected?
Microsoft Word Microsoft 365 Apps, Office 2019, Office LTSC 2021/2024, Office for Mac, SharePoint Server.
Is there a fix for CVE-2026-55127?
A patch was published on 2026-07-14: Security updates made available via Microsoft MSRC. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
How is CVE-2026-55127 attacked?
It is attacked with local access, in a network appliance.
Am I affected by CVE-2026-55127?
Check whether you run Microsoft SharePoint Server or Microsoft Word 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 Microsoft Office Word. The vulnerability is triggered when the application fails to properly validate input while processing a specially crafted document. An attacker can exploit this by convincing a user to open a malicious file, leading to arbitrary code execution in the context of the current user. The attack vector is local with a requirement for user interaction (UI:R). Affected products include various versions of Microsoft Office (2019, LTSC 2021/2024), Microsoft 365 Apps, and SharePoint Server. Microsoft has released security updates to address this issue.

Affected products

  • Microsoft Microsoft Office Word Microsoft 365 Apps, Office 2019, Office LTSC 2021/2024, Office for Mac, SharePoint Server

Timeline

  • 2026-07-14: advisory: Initial disclosure by Microsoft and NVD publication.
  • 2026-07-14: patched: Security updates made available via Microsoft MSRC.

References

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