How severe is CVE-2026-45498?

CVE-2026-45498 has a CVSS 3.x base score of 4.0, rated medium severity. It is exploitable over local access with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability low.

Is CVE-2026-45498 being actively exploited?

Yes. CVE-2026-45498 is on CISA's Known Exploited Vulnerabilities (KEV) catalog, added on 2026-05-20, which means active exploitation has been confirmed. It should be prioritised for remediation.

What products are affected by CVE-2026-45498?

CVE-2026-45498 affects Microsoft Defender Antimalware Platform. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2026-45498?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Because this CVE is known to be actively exploited, treat remediation as urgent — CISA KEV typically sets a short remediation deadline.

Does CVE-2026-45498 have an EU (EUVD) identifier?

Yes. CVE-2026-45498 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-31102. It is also flagged as exploited in the EUVD (since 2026-05-20).

When was CVE-2026-45498 published?

CVE-2026-45498 was published on 2026-05-20 and last updated on 2026-06-17.

CVE-2026-45498

CVE-2026-45498 is a medium-severity vulnerability in Microsoft Defender Antimalware Platform with a CVSS 3.x base score of 4.0. It is listed in CISA's Known Exploited Vulnerabilities (KEV) catalog, confirming it has been exploited in the wild (added 2026-05-20). The underlying weakness is classified as CWE-400.

Key facts

Severity: Medium (CVSS 3.x base score 4.0)
EPSS exploit prediction: 63% (99th percentile)
Actively exploited: Yes — listed in CISA KEV (added 2026-05-20)
EU (EUVD) id: EUVD-2026-31102
EU exploitation: Flagged exploited in the ENISA EU Vulnerability Database (since 2026-05-20)
Weakness: CWE-400
Affected product: Microsoft Defender Antimalware Platform
Published: 2026-05-20
Last modified: 2026-06-17

Description

Microsoft Defender Denial of Service Vulnerability

Frequently asked questions

What is CVE-2026-45498?: Microsoft Defender Denial of Service Vulnerability
How severe is CVE-2026-45498?: CVE-2026-45498 has a CVSS 3.x base score of 4.0, rated medium severity. It is exploitable over local access with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability low.
Is CVE-2026-45498 being actively exploited?: Yes. CVE-2026-45498 is on CISA's Known Exploited Vulnerabilities (KEV) catalog, added on 2026-05-20, which means active exploitation has been confirmed. It should be prioritised for remediation.
What products are affected by CVE-2026-45498?: CVE-2026-45498 affects Microsoft Defender Antimalware Platform. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2026-45498?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Because this CVE is known to be actively exploited, treat remediation as urgent — CISA KEV typically sets a short remediation deadline.
Does CVE-2026-45498 have an EU (EUVD) identifier?: Yes. CVE-2026-45498 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-31102. It is also flagged as exploited in the EUVD (since 2026-05-20).
When was CVE-2026-45498 published?: CVE-2026-45498 was published on 2026-05-20 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:a:microsoft:defender_antimalware_platform:*:*:*:*:*:*:*:*

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