Microsoft Defender Denial of Service Vulnerability

[ Why it matters ]Priority signals

• Exploited in the wild: on CISA's Known Exploited Vulnerabilities list since 2026-05-20

[ Description ]Official description

Microsoft Defender Denial of Service Vulnerability

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

[ Fixes ]Fixes and patches

CISA required action (US federal deadline 3 Jun 2026): Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.

No fix or interim patch is linked from our sources yet. Check the vendor references below and limit exposure of affected systems until a fix is available.

[ References ]References

• msrc.microsoft.com/update-guide/vulnerability/CVE-2026-45498Vendor Advisory
• www.cisa.gov/known-exploited-vulnerabilities-catalogThird Party AdvisoryUS Government Resource