# CVE-2026-45498

Microsoft Defender Denial of Service Vulnerability

- Page: https://www.vulneraibility.com/cve/CVE-2026-45498
- CVSS: 4.0
- Known exploited: yes, in CISA KEV since 2026-05-20; CISA due date 2026-06-03
- EPSS: 63.08%
- Unvetted proof-of-concept code on GitHub: 1 GitHub proof of concept (first 2026-07-02)
- CISA SSVC: exploitation active, automatable no, technical impact partial (assessed 2026-05-21)
- Weakness: CWE-400
- Published: 2026-05-20

## Affected versions

- Microsoft Microsoft Defender Antimalware Platform: affected >= 4.0.0.0 and < 4.18.26040.7

A version outside these ranges is not a statement that it is unaffected.

## References

- [patch] https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-45498
- [other] https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2026-45498

---
Summary, impact and action are written by the vulneraibility.com AI analysis pipeline from the CVE record, NVD, CISA and FIRST data; verify against the references.