How severe is CVE-2020-5665?

CVE-2020-5665 has a CVSS 3.x base score of 7.4, rated high severity. It is exploitable over an adjacent network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.

Is CVE-2020-5665 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (58th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2020-5665?

CVE-2020-5665 affects Mitsubishielectric Melsec Iq-f Fx5u Cpu Firmware. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2020-5665?

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.

When was CVE-2020-5665 published?

CVE-2020-5665 was published on 2020-12-14 and last updated on 2026-06-17.

CVE-2020-5665

CVE-2020-5665 is a high-severity vulnerability in Mitsubishielectric Melsec Iq-f Fx5u Cpu Firmware with a CVSS 3.x base score of 7.4. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low.

Key facts

Severity: High (CVSS 3.x base score 7.4)
CVSS v2: 3.3
EPSS exploit prediction: 1% (58th percentile)
Actively exploited: Not listed in CISA KEV
Affected product: Mitsubishielectric Melsec Iq-f Fx5u Cpu Firmware
Published: 2020-12-14
Last modified: 2026-06-17

Description

Improper check or handling of exceptional conditions in MELSEC iQ-F series FX5U(C) CPU unit firmware version 1.060 and earlier allows an attacker to cause a denial-of-service (DoS) condition on program execution and communication by sending a specially crafted ARP packet.

Frequently asked questions

What is CVE-2020-5665?: Improper check or handling of exceptional conditions in MELSEC iQ-F series FX5U(C) CPU unit firmware version 1.060 and earlier allows an attacker to cause a denial-of-service (DoS) condition on program execution and communication by sending a specially crafted ARP packet.
How severe is CVE-2020-5665?: CVE-2020-5665 has a CVSS 3.x base score of 7.4, rated high severity. It is exploitable over an adjacent network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.
Is CVE-2020-5665 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (58th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2020-5665?: CVE-2020-5665 affects Mitsubishielectric Melsec Iq-f Fx5u Cpu Firmware. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2020-5665?: 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.
When was CVE-2020-5665 published?: CVE-2020-5665 was published on 2020-12-14 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:o:mitsubishielectric:melsec_iq-f_fx5u_cpu_firmware:*:*:*:*:*:*:*:*