CVE-2026-55056 Microsoft CVE debrief

Who should care

Users of Microsoft Office, particularly those using 365 Apps, Office 2016, Office 2019, Office 2021, and Office 2024, should be aware of this vulnerability and take necessary precautions. This includes administrators, security teams, and operators who manage or use these Office versions.

Technical summary

A heap-based buffer overflow vulnerability exists in Microsoft Office, which could allow an unauthorized attacker to execute code locally. The vulnerability has been assigned a CVSS score of 7.8 and a severity of HIGH. It affects various versions of Microsoft Office, including 365 Apps, Office 2016, Office 2019, Office 2021, and Office 2024.

Defensive priority

High priority should be given to patching or mitigating this vulnerability, as it could allow an attacker to execute code locally. Implementing compensating controls and conducting inventory checks can also help reduce the risk associated with this vulnerability.

Recommended defensive actions

• Apply patches or updates provided by Microsoft to vulnerable Office versions.
• Implement compensating controls, such as monitoring for suspicious activity.
• Conduct inventory checks to identify and prioritize vulnerable systems.
• Consider disabling or restricting access to vulnerable Office features or components.

Evidence notes

The CVE record and NVD detail provide information on the vulnerability, including its CVSS score, severity, and affected products. However, the exact scope of affected systems and potential attack vectors are not explicitly stated. The source item URL and vendor advisory also provide context for this vulnerability. Defenders should verify the affected scope and vendor guidance for accurate information.

Official resources