How severe is CVE-2026-45498?

CVE-2026-45498 has a CVSS 3.1 base score of 4 (MEDIUM). EPSS estimates a 1.3% probability of exploitation in the next 30 days. It is listed in the CISA Known Exploited Vulnerabilities catalog.

CVE-2026-45498: Microsoft Defender Denial of Service

CISA Known Exploited Vulnerabilities

Microsoft Defender Denial of Service Vulnerability is confirmed as actively exploited and is listed in the CISA KEV catalog.

Added to KEV

2026-05-20

Remediation due

2026-06-03

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.

CISA notes
https://msrc.microsoft.com/update-guide/en-US/vulnerability/CVE-2026-45498 ; https://nvd.nist.gov/vuln/detail/CVE-2026-45498

Description

Microsoft Defender Denial of Service Vulnerability

Severity

CVSS 3.1 · CNA4 MEDIUM

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

SSVC · CISA-ADP

Exploitationactive

Automatableno

Technical impactpartial

Affected Products

Vendor	Product	Affected versions
Microsoft	Microsoft Defender Antimalware Platform	4.0.0.0 to <4.18.26040.7

References

1 Links

Vendor advisories

Microsoft Defender Denial of Service Vulnerability

Record Details

Published

2026-05-20

Last updated

2026-08-10

Assigner (CNA)

microsoft

Credited to

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Related Tool Categories

Tool categories that test for or protect against this vulnerability class.

CWE-400 · Uncontrolled Resource Consumption

Fuzzing

CVE record data © The MITRE Corporation, used under the CVE Terms of Use. Exploited-in-the-wild data from the CISA Known Exploited Vulnerabilities catalog (CC0). Exploit prediction scores by FIRST EPSS (first.org/epss). This site is not endorsed or certified by MITRE, NVD, CISA, or FIRST.