CVE-2026-64918 and is rated Medium severity with a CVSS score of 6.5. It is not in the current CISA KEV record we collected. That does not prove exploitation has not occurred.
What to do next
Remediation and response
Microsoft Security Response Center guidance
Vendor revision: Sep 8, 2026
Release Notes
Vendor-listed releases
https://aka.ms/OfficeSecurityReleases
CISA KEVNot listedBased on the latest collected catalog
EPSS0.9%Estimated 30-day exploitation probability
Ransomware useNot markedCISA KEV ransomware field
Threat actors0Source-linked actor relationships
Overview
What is CVE-2026-64918?
Insufficiently protected credentials in Microsoft Office allows an unauthorized attacker to perform spoofing over a network.