Which products and versions are affected by CVE-2026-45498?

Affected: Defender Antimalware Platform (Microsoft) versions >= 4.0.0.0; Microsoft Defender. The full list is in the CVE brief.

Is CVE-2026-45498 being exploited in the wild?

It is exploited in the wild, listed in CISA KEV, Industry KEV feed, CIRCL KEV, ENISA EUVD since May 19, 2026.

Is CVE-2026-45498 in the CISA KEV catalog?

Yes. It was added on May 20, 2026 with a federal remediation due date of Jun 3, 2026.

Is there a public exploit for CVE-2026-45498?

Public exploit code is available.

Is there a fix for CVE-2026-45498?

Fixed versions are available, including Defender Antimalware Platform 4.18.26040.7.

How urgently should CVE-2026-45498 be patched?

Brandefense priority: patch immediately, because it is listed as exploited in the wild.

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Vulnerability Intelligence

CVE-2026-45498

HighExploitedPublic exploit

Microsoft Defender Denial of Service Vulnerability

Published May 20, 2026 · Updated Aug 10, 2026 · Also known as EUVD-2026-31102, GHSA-8gp3-pghr-6wxp

Key Facts

Patch immediately

CVE-2026-45498 is a high-severity vulnerability (CVSS 7.5 v3.1) affecting Defender Antimalware Platform (Microsoft), Microsoft Defender.
It is exploited in the wild, listed in CISA KEV, Industry KEV feed, CIRCL KEV, ENISA EUVD since May 19, 2026. Public exploit code is available.
EPSS estimates a 1.3% probability of exploitation in the next 30 days.
Fixed versions are available, including Defender Antimalware Platform 4.18.26040.7.
Brandefense priority: patch immediately, because it is listed as exploited in the wild.

CVSS v3.1

7.5

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

EPSS (30-day exploit likelihood)

1.3%

Exploited in the wild

Yes

4 catalog listings

Public exploit code

Available

Proof-of-concept or weaponized module

Get the full CVE-2026-45498 brief as a PDF

Every affected product and fixed release, exploitation status and a first 24 hours response checklist, emailed within minutes.

Description

Microsoft Defender Denial of Service Vulnerability

Known-Exploited Catalog Listings

Catalog	Added	Remediation due	Ransomware use
CISA KEV	May 20, 2026	Jun 3, 2026	Not reported
Industry KEV feed	May 19, 2026	Jun 3, 2026	Not reported
CIRCL KEV	May 20, 2026	Jun 3, 2026	Not reported
ENISA EUVD	May 20, 2026	n/a	Not reported

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.

Affected Products

4 affected entries in total

Product	Affected versions	Fixed in
Defender Antimalware PlatformMicrosoft	>= 4.0.0.0	4.18.26040.7
Microsoft DefenderMicrosoft	See advisory	n/a

Patched Releases

Defender Antimalware Platform

4.18.26040.7

Timeline

Added to Industry KEV feed
May 19, 2026
Publicly disclosed
May 20, 2026
Added to CISA KEV
May 20, 2026
Added to CIRCL KEV
May 20, 2026
Added to ENISA EUVD
May 20, 2026
Last updated
Aug 10, 2026

Weakness Type

CWE-400 Uncontrolled Resource Consumption

References

FAQ

Common Questions.

Microsoft Defender Denial of Service Vulnerability
Affected: Defender Antimalware Platform (Microsoft) versions >= 4.0.0.0; Microsoft Defender. The full list is in the CVE brief.
It is exploited in the wild, listed in CISA KEV, Industry KEV feed, CIRCL KEV, ENISA EUVD since May 19, 2026.
Yes. It was added on May 20, 2026 with a federal remediation due date of Jun 3, 2026.
Public exploit code is available.
Fixed versions are available, including Defender Antimalware Platform 4.18.26040.7.
Brandefense priority: patch immediately, because it is listed as exploited in the wild.

Is CVE-2026-45498 Running On Your Attack Surface?

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