How severe is CVE-2026-45584?

CVE-2026-45584 has a CVSS 3.x base score of 8.1, rated high severity. It is exploitable over network with high attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.

Is CVE-2026-45584 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (54th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2026-45584?

CVE-2026-45584 affects Microsoft Malware Protection Engine. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2026-45584?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.

Does CVE-2026-45584 have an EU (EUVD) identifier?

Yes. CVE-2026-45584 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-31105.

When was CVE-2026-45584 published?

CVE-2026-45584 was published on 2026-05-20 and last updated on 2026-06-17.

CVE-2026-45584

CVE-2026-45584 is a high-severity vulnerability in Microsoft Malware Protection Engine with a CVSS 3.x base score of 8.1. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-122.

Key facts

Severity: High (CVSS 3.x base score 8.1)
EPSS exploit prediction: 1% (54th percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2026-31105
Weakness: CWE-122
Affected product: Microsoft Malware Protection Engine
Published: 2026-05-20
Last modified: 2026-06-17

Description

Heap-based buffer overflow in Microsoft Defender allows an unauthorized attacker to execute code over a network.

Frequently asked questions

What is CVE-2026-45584?: Heap-based buffer overflow in Microsoft Defender allows an unauthorized attacker to execute code over a network.
How severe is CVE-2026-45584?: CVE-2026-45584 has a CVSS 3.x base score of 8.1, rated high severity. It is exploitable over network with high attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.
Is CVE-2026-45584 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (54th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-45584?: CVE-2026-45584 affects Microsoft Malware Protection Engine. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2026-45584?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
Does CVE-2026-45584 have an EU (EUVD) identifier?: Yes. CVE-2026-45584 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-31105.
When was CVE-2026-45584 published?: CVE-2026-45584 was published on 2026-05-20 and last updated on 2026-06-17.

References

https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-45584

Affected products (1)

cpe:2.3:a:microsoft:malware_protection_engine:*:*:*:*:*:*:*:*

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