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Known exploited vulnerability

CVE-2026-45498

highCVSS 3.1 7.5In CISA KEVEPSS 63%Published · Microsoft

The short answer

CVE-2026-45498 affects Microsoft Microsoft Defender Antimalware Platform and is rated high (CVSS 7.5). CISA added it to the Known Exploited Vulnerabilities catalog on 2026-05-20: attackers are using it, so patch it first.

What it is

Microsoft Defender Denial of Service Vulnerability

Weakness: CWE-400.

Severity

7.5 high

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

Exploited (CISA KEV)

Yes, since May 20, 2026

Federal due date Jun 3, 2026

EPSS, next 30 days

63%

Higher than 99% of scored CVEs

How it can be exploited

Attack vector
Network
Attack complexity
Low
Privileges required
None
User interaction
None
Scope
Unchanged
Confidentiality impact
None
Integrity impact
None
Availability impact
High

What CISA says 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.

Affected products

Microsoft Defender Antimalware Platform. NVD's record lists the exact affected versions.

References

Questions

Is CVE-2026-45498 being exploited?

Yes. CISA added CVE-2026-45498 to its Known Exploited Vulnerabilities catalog on 2026-05-20, with a federal remediation due date of 2026-06-03.

How do I fix CVE-2026-45498?

CISA's 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.

From NVD, CISA KEV, FIRST EPSS and OSV.dev, checked . Status on NVD: Analyzed. The description is NVD's text, quoted as published.

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