Microsoft Defender Denial of Service Vulnerability

HIGH 7.5EXPLOITED (CISA KEV)CVE-2026-45498 · Published 20/05/2026 · updated 23/07/2026

Microsoft Defender Denial of Service Vulnerability. Actively exploited: CISA added this vulnerability to its Known Exploited Vulnerabilities catalog on 20/05/2026. Patch affected systems as an emergency.

Package	Affected versions	Patched versions
defender antimalware platform microsoft	`< 4.18.26040.7`	`4.18.26040.7`

Description

References

msrc.microsoft.com/update-guide/vulnerability/CVE-2026-45498 · Vendor Advisory
cisa.gov/known-exploited-vulnerabilities-catalog · Third Party Advisory
CISA KEV · CVE-2026-45498

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