CVE-2026-55024 Microsoft CVE debrief

Who should care

Defenders and IT administrators responsible for Microsoft Office products should assess exposure and apply patches. This vulnerability requires immediate attention due to its high CVSS score and potential impact.

Why it matters

CVE-2026-55024 is a high-severity vulnerability in Microsoft Excel that allows local code execution. Defenders and IT administrators should assess exposure and apply patches immediately.

• Local code execution is possible due to type confusion in Microsoft Excel
• Multiple Microsoft Office products and versions are affected
• Patches are available from Microsoft

Technical summary

The vulnerability is due to a type confusion in Microsoft Office Excel, allowing an unauthorized attacker to execute code locally. Multiple Microsoft Office products and versions are affected, including Microsoft 365 Apps for Enterprise, Microsoft Excel 2016, Microsoft Office 2019, and others.

Defensive priority

High

Recommended defensive actions

• Apply patches from Microsoft for affected Office products
• Inventory and assess exposure of Microsoft Office products
• Verify patch deployment for Microsoft Office products

Evidence notes

The CVE Program record and NVD vulnerability detail provide official information on the vulnerability. Microsoft's security update guide provides patch information.

Sources and references

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.