CVE-2026-45498: listed in the CISA KEV catalog

CVE-2026-45498 · CVSS 4.0 MEDIUM · EPSS 1% · KEV 2026-05-20 · patch available

Microsoft Defender Denial of Service Vulnerability

Is CVE-2026-45498 exploited?

• Listed in the CISA KEV catalog on 2026-05-20.
• Federal remediation due 2026-06-03.
• Past that date by 120 days.
• EPSS puts exploitation in the next 30 days at 1%.
• Public exploit code: none found in monitored sources.

Which products and versions are affected?

• Microsoft · Microsoft Defender Antimalware Platform · < 4.18.26040.7

Is there a patch?

• Release Notes

What PlainSec published about CVE-2026-45498

• BigDiskBuster Keeps Defender Stuck on Old Signatures (2026-09-23)

Primary sources

• NVD record
• CISA KEV catalog

KEV and EPSS are re-checked daily. Record last updated 2026-09-24.