CVE-2026-45498KEV · OVERDUECWE-400

Microsoft Defender Denial of Service Vulnerability

Medium · published May 20, 2026

Patch now

The score understates this — it's already being exploited

CVSS calls it medium at 4.0. It is confirmed in active exploitation. It sits in the 69.6th percentile for exploit probability.

143
days past CISA
deadline
CVSS v3.1
4.0
EPSS
1%
Percentile
69.6
In the wild
Confirmed
What it is

Microsoft Defender Denial of Service Vulnerability

The record
Technical detail
CVSS v3.1
4.0 · MEDIUM
Vector
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
CVSS v4.0
Not supplied
EPSS
0.01267 · 69.6th percentile
Weakness
CWE-400 · Uncontrolled Resource Consumption
Published
2026-05-20T13:09Z
KEV added
2026-05-20 · due 2026-06-03
EPSS history
Timeline
  • 25 SEP 03:26Z
    EPSS moved 63% → 1%
    epss
  • 20 MAY 13:09Z
    Microsoft Defender Denial of Service Vulnerability
    cvelistv5
  • 20 MAY 00:00Z
    Added to CISA KEV — remediate by Jun 3
    kev