ACTIVELY EXPLOITED

CVE-2026-45498: Microsoft Defender Denial of Service Vulnerability

Facts
VendorMicrosoft
ProductDefender
Actively exploitedYes
Added to CISA KEV20 May 2026
CISA federal deadline3 Jun 2026

Required action (CISA's text)

Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.

Description (NVD)

Microsoft Defender contains an unspecified vulnerability that allows for denial of service.

SOURCES

Other Microsoft flaws

Data from NVD, CISA KEV, FIRST EPSS and vendor advisories. Updated 10 Nov 2026.