CVE-2026-55049: Microsoft Office heap buffer overflow code execution

CVE-2026-55049 · Severity: high · CVSS 7.8 · Published 2026-07-14

Microsoft Office is a widely used suite of productivity applications including Word, Excel, and PowerPoint. A security vulnerability has been identified that could allow an attacker to execute malicious code on a user's computer if the user is tricked into opening a specially crafted file. Successful exploitation could lead to a full compromise of the user's data and the ability for an attacker to perform unauthorized actions on the affected system.

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. Vendors: Microsoft.

Quick answers

Is CVE-2026-55049 exploited in the wild?
No. Junglewise Threat Intelligence has no report of CVE-2026-55049 being exploited in the wild.
How severe is CVE-2026-55049?
High severity, with a CVSS score of 7.8, 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 4 more.
Is there a fix for CVE-2026-55049?
A patch was published on 2026-07-14: Security updates made available via Microsoft Update Guide Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
How is CVE-2026-55049 attacked?
It is attacked with local access, in a network appliance.
Am I affected by CVE-2026-55049?
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 vulnerability (CWE-122) exists in multiple versions of Microsoft Office across Windows and macOS platforms. The flaw is triggered when the application improperly handles memory allocation while processing a maliciously crafted file. An attacker can exploit this by convincing a user to open a specially crafted document, leading to arbitrary code execution in the context of the current user. The attack vector is local, requiring user interaction (UI:R), but does not require prior administrative privileges. Microsoft has released security updates to address this issue across affected Office 2016, 2019, 2021, 2024, and 365 versions.

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

Timeline

  • 2026-07-14: advisory: Initial disclosure by Microsoft and NVD
  • 2026-07-14: patched: Security updates made available via Microsoft Update Guide

References

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