CVE-2026-64904 Microsoft CVE debrief

Who should care

Defenders responsible for Microsoft Office deployments should assess exposure and prioritize remediation. This includes reviewing and patching vulnerable Microsoft Office versions to prevent local code execution. Security teams and vulnerability management teams should also be aware of the potential impact and take necessary actions to mitigate the vulnerability.

Why it matters

CVE-2026-64904 is a high-severity vulnerability in Microsoft Office that allows an unauthorized attacker to execute code locally. Defenders should prioritize patching vulnerable versions and assess exposure.

• Verify and patch vulnerable Microsoft Office versions to prevent local code execution
• Assess exposure and prioritize remediation for affected products
• Monitor for potential exploitation attempts

Technical summary

A type confusion vulnerability in Microsoft Office allows an unauthorized attacker to execute code locally. This vulnerability, tracked as CVE-2026-64904, has a CVSS severity rating of HIGH and a score of 7.8. The vulnerability affects Microsoft Office and requires defenders to assess exposure and prioritize remediation. The technical impact is significant, as it allows for local code execution.

Defensive priority

Defenders should prioritize patching vulnerable Microsoft Office versions and assess exposure.

Recommended defensive actions

• Patch vulnerable Microsoft Office versions
• Assess exposure and prioritize remediation
• Verify inventory for affected products

Evidence notes

The CVE record and NVD entry provide details on the vulnerability, but additional information is limited. The CVE Program record (CVE-2026-64904) and NVD detail page offer source-provided CVE metadata and vulnerability assessments. A vendor advisory and patch information are also available (ref-4). However, the scope of affected products and versions may require further verification by defenders.

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.