No exploitation reported

CVE-2020-5665

No exploitation reported by the sources we read.

Published2020-12-14

Am I affected?

With a domain, we read the version its public headers and pages expose. A distribution build can carry the fix under an older number.

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.

Timeline

dates in UTC

2020-12-1403:15CVE publishedNVD

Observed activity

isMalicious corpus · updated 2026-10-23 18:48 UTC

Indicators tagged with this CVE, per day0 indicators over 7 days

Block these indicators

Firewall list (EDL, text): https://api.ismalicious.com/edl/cve/CVE-2020-5665?format=txt
CSV export: https://api.ismalicious.com/edl/cve/CVE-2020-5665?format=csv
TAXII collection of exploited CVEs
The EDL and CSV take an API key on the Pro plan.

Versions per branch

NVD

Mitsubishielectric melsec iq-f fx5u cpu firmwareversion to verify

Branch	Affected	Fixed in	Source
1.60	≤ 1.060	no fix published	NVD

as publishedRanges as NVD and OSV publish them; a distribution’s build can be fixed under an older number.

Distribution builds and vendor advisories

Packages from OSV.dev and products from the vendors' CSAF advisories.

version not verifiedVersions not verified: read as OSV.dev and the vendors publish them, not checked against each vendor's release list.

Vendor advisories

ICSA-20-345-01 CISA1 known affected
Mitsubishi Electric MELSEC iQ-F Series
MELSEC iQ-F Series - FX5U(C) CPU module: firmware Version 1.060 or earlier

Full record on NVD

Fix

Mitigation from the vendor CISA ICSA-20-345-01 · 1 productMitsubishi Electric recommends users update firmware to Version 1.061 or later.
Mitigation from the vendor CISA ICSA-20-345-01 · 1 productUse a firewall or virtual private network to prevent unauthorized access when Internet access is required.
Mitigation from the vendor CISA ICSA-20-345-01 · 1 productUse within the LAN and ensure that they are not accessible from untrusted networks and hosts.

Advisories and patches

www.mitsubishielectric.co.jpVendor Advisory
www.mitsubishielectric.comVendor Advisory

Detection

Nuclei template: none so far
Exploit-DB: no entry
Proof-of-concept repositories: none listed

Sources

NVDCVSS 3.17.4read 2026-10-23
NVDCVSS 2.03.3read 2026-10-23
FIRST EPSSEPSS score1.0 %2026-10-22

Technical details

CVSS v3 Vector: CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H
Published: 2020-12-14
Last Modified: 2026-06-17
NVD status: Modified

Frequently asked questions

What is CVE-2020-5665?

Is CVE-2020-5665 actively exploited?

Active exploitation of CVE-2020-5665 has not been confirmed. Its EPSS score was 1.0% on 2026-10-22, the estimated probability of exploitation in the next 30 days.

What is the CVSS score for CVE-2020-5665?

CVE-2020-5665 has a CVSS v3 base score of 7.4 (HIGH severity), with vector string CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H.

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