CVE-2026-81401 Microsoft CVE debrief

Who should care

Defenders responsible for Microsoft Office and Microsoft 365 Apps installations should assess exposure and prioritize patching vulnerable systems.

Why it matters

CVE-2026-81401 is a medium-severity vulnerability in Microsoft Office Excel that allows information disclosure via type confusion. Defenders should prioritize patching vulnerable systems, especially those with local access to Excel, and assess exposure of Microsoft Office and Microsoft 365 Apps installations.

• Potential information disclosure via type confusion in Excel
• Need to verify patching and configuration of vulnerable systems
• Possible local exploitation by unauthorized attackers

Technical summary

CVE-2026-81401 is a type confusion vulnerability in Microsoft Office Excel that allows an unauthorized attacker to disclose information locally. The vulnerability has a CVSS score of 5.5 and affects various versions of Microsoft Office and Microsoft 365 Apps.

Defensive priority

Defenders should prioritize patching vulnerable systems, especially those with local access to Excel.

Recommended defensive actions

• Patch vulnerable systems, especially those with local access to Excel
• Inventory and assess exposure of Microsoft Office and Microsoft 365 Apps installations
• Monitor for potential information disclosure attempts

Evidence notes

The CVE record and NVD entry provide details on the vulnerability, including its CVSS score and affected products. However, specific version information and exploitation details are not provided.

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.