CVE-2026-78507 and is rated High severity with a CVSS score of 8.8. 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 17, 2026
Vendor remediation details
Release Notes
Vendor-listed releases
16.0.10417.20207
16.0.20326.20138
16.113.26091433
16.0.14334.20906
16.0.17932.20976
CISA KEVNot listedBased on the latest collected catalog
EPSS0.8%Estimated 30-day exploitation probability
Ransomware useNot markedCISA KEV ransomware field
Threat actors0Source-linked actor relationships
Overview
What is CVE-2026-78507?
Use after free in Microsoft Office Word allows an unauthorized attacker to execute code over a network.