CVE-2026-45498

Published May 20, 2026

Last updated 17 days ago

Exploit known CVSS medium 4.0

Microsoft Defender

Zero-day

API

Overview

AI description

Automated description summarized from trusted sources.

CVE-2026-45498 is identified as a denial-of-service (DoS) vulnerability affecting the Microsoft Defender Antimalware Platform. This flaw can be exploited to prevent Microsoft Defender from functioning as intended, potentially disrupting its protective capabilities on unpatched Windows devices. Microsoft has acknowledged that this vulnerability has been exploited in the wild, and security patches have been released to address it. The affected versions include Microsoft Defender Antimalware Platform 4.18.26030.3011 and earlier.

Description: Microsoft Defender Denial of Service Vulnerability
Source: secure@microsoft.com
NVD status: Analyzed
Products: defender_antimalware_platform

Risk scores

CVSS 3.1

Type: Primary
Base score: 7.5
Impact score: 3.6
Exploitability score: 3.9
Vector string: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Severity: HIGH

Known exploits

Data from CISA

Vulnerability name: Microsoft Defender Denial of Service Vulnerability
Exploit added on: May 20, 2026
Exploit action due: Jun 3, 2026
Required action: Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.

Weaknesses

secure@microsoft.com: CWE-400

Hype score: Not currently trending

Configurations

[
  {
    "nodes": [
      {
        "cpeMatch": [
          {
            "criteria": "cpe:2.3:a:microsoft:defender_antimalware_platform:*:*:*:*:*:*:*:*",
            "matchCriteriaId": "7DBA2812-3139-4628-9CE5-FB2241242A6C",
            "versionEndExcluding": "4.18.26040.7",
            "vulnerable": true
          }
        ],
        "negate": false,
        "operator": "OR"
      }
    ]
  }
]

References

Sources include official advisories and independent security research.