Published May 20, 2026Sources checked Nov 14, 2026
8.1HIGHCVSS out of 10
What this means
Review the available evidence
CVE-2026-45584 and is rated High severity with a CVSS score of 8.1. 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: May 26, 2026
Release Notes
Vendor-listed releases
1.1.26040.8
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-2026-45584?
Heap-based buffer overflow in Microsoft Defender allows an unauthorized attacker to execute code over a network.