HOMEVULNERABILITIESCVE-2020-5666
HIGH

CVE-2020-5666

CWE-400Published: November 16, 2020· Updated: Jun 17, 2026

7.5
CVSS v3.1

Official Description

Uncontrolled resource consumption vulnerability in MELSEC iQ-R Series CPU Modules (R00/01/02CPU Firmware versions from '05' to '19' and R04/08/16/32/120(EN)CPU Firmware versions from '35' to '51') allows a remote attacker to cause an error in a CPU unit via a specially crafted HTTP packet, which may lead to a denial-of-service (DoS) condition in execution of the program and its communication.

NVD Source

Technical Analysis

CVE-2020-5666 can be exploited remotely over the network without requiring physical or adjacent access, significantly expanding the attack surface for threat actors.

The vulnerability requires no privileges and no user interaction, making it a prime target for automated exploitation campaigns and worm-like propagation.

A successful exploit results in availability disruption (denial of service), with a CVSS base score of 7.5.

CVSS v3.1 Vector Breakdown

Exploitability
Attack VectorNetwork
Attack ComplexityLow
Privileges Req.None
User InteractionNone
ScopeUnchanged
Impact
ConfidentialityNone
IntegrityNone
AvailabilityHigh
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Affected Vendors & Products

mitsubishielectric16 product(s)
melsec iq-r00 firmwaremelsec iq-r00melsec iq-r01 firmwaremelsec iq-r01melsec iq-r02 firmwaremelsec iq-r02melsec iq-r04 firmwaremelsec iq-r04melsec iq-r16 firmwaremelsec iq-r16melsec iq-r08 firmwaremelsec iq-r08+4
Source: NVD CPE · 16 total CPE entries

Exploit & PoC Resources

NO KNOWN EXPLOITNo public exploit confirmed at this time
Exploit-DB
Offensive Security exploit database
GitHub PoC Search
Community PoC repositories
Rapid7 / Metasploit
Metasploit module search
PacketStorm
Security advisories & exploits
NVD Detail
Official NIST entry
MITRE CVE
CVE Program entry
External links open in a new tab. Always verify in a controlled environment before use.

Official Patches & Advisories

ADVISORYhttps://jvn.jp/en/jp/JVN44764844/index.html
ADVISORYhttps://jvn.jp/jp/JVN44764844/index.html
ADVISORYhttps://us-cert.cisa.gov/ics/advisories/icsa-20-317-01
ADVISORYhttps://www.mitsubishielectric.com/en/psirt/vulnerability/pdf/2020-015_en.pdf
ADVISORYhttps://jvn.jp/en/jp/JVN44764844/index.html
ADVISORYhttps://jvn.jp/jp/JVN44764844/index.html
ADVISORYhttps://us-cert.cisa.gov/ics/advisories/icsa-20-317-01
ADVISORYhttps://www.mitsubishielectric.com/en/psirt/vulnerability/pdf/2020-015_en.pdf

All References (8)

→
https://jvn.jp/en/jp/JVN44764844/index.htmlThird Party Advisory
→
https://jvn.jp/jp/JVN44764844/index.htmlThird Party Advisory
→
https://us-cert.cisa.gov/ics/advisories/icsa-20-317-01Third Party Advisory · US Government Resource
→
https://www.mitsubishielectric.com/en/psirt/vulnerability/pdf/2020-015_en.pdfMitigation · Vendor Advisory
→
https://jvn.jp/en/jp/JVN44764844/index.htmlThird Party Advisory
→
https://jvn.jp/jp/JVN44764844/index.htmlThird Party Advisory
→
https://us-cert.cisa.gov/ics/advisories/icsa-20-317-01Third Party Advisory · US Government Resource
→
https://www.mitsubishielectric.com/en/psirt/vulnerability/pdf/2020-015_en.pdfMitigation · Vendor Advisory

Quick Facts

CVE IDCVE-2020-5666
CVSS Score7.5 / 10
SeverityHIGH
WeaknessCWE-400
CISA KEVNo
Affected1 vendor(s)
PublishedNov 16, 2020

Related CVEs (CWE-400)

CVE-2024-45166
9.8
CVE-2025-24190
9.8
CVE-2023-28507
9.8
CVE-2024-39462
9.8
CVE-2023-30769
9.8
CVE-2025-24269
9.8

Recommended Actions

  • →Apply vendor patches immediately
  • →Monitor CVE-2020-5666 in threat intel feeds
  • →Review IDS/IPS signatures for exploitation attempts
Data sourced from NVD (NIST), CISA KEV, and EPSS (FIRST). Analysis generated by CTIWATCH.COM. CVE data is provided under the NVD usage policy.
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