CVE-2026-45498
Microsoft Defender Denial of Service Vulnerability
- Medium 4.0
- Exploited: added to CISA KEV 20 May 2026
Description
Microsoft Defender Denial of Service Vulnerability
Key facts
- Published
- 20 May 2026
- Last changed
- 10 Aug 2026
- Assigned by
- microsoft
- KEV added
- 20 May 2026
- KEV fix due
- 3 Jun 2026
- EPSS
- 63.076% likely to be exploited in the next 30 days, higher than 99.215% of CVEs (scores for 15 Nov 2026)
- SSVC (CISA)
- Exploitation: active; Automatable: no; Technical impact: partial
Severity scores
Each score is shown as its source gave it. They are not averaged or merged.
- 4.0CVSS 3.1, Mediumfrom the CNA (microsoft)
CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L/E:U/RL:O/RC:C
What to do
- Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.CISA KEV required action
Historical context and remediation
This reference retains the original CVE publication date. A recent record update does not mean a new attack occurred.
No separately sourced impact summary is available on this page yet. Consult the description, version data and dated exploitation evidence.
Version statuses below come from the CNA. An “unaffected” version is not necessarily a currently supported release or proof of a patch date. EPSS is a dated risk estimate, not a count of historical attacks.
Affected products
| Vendor | Product | Versions |
|---|---|---|
| Microsoft | Microsoft Defender Antimalware Platform |
|
Timeline
- 20 May 2026 Added to the CISA KEV catalogue
- 20 May 2026 Published