CVE-2020-5666

Name: CVE-2020-5666
Creator: NVD / NIST
Published: 2020-11-16T01:15:13.327+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

HIGHCVSS 7.5/10EPSS 8.40%

Last modified Jun 17, 2026

CVE-2020-5666 is a high-severity vulnerability rated 7.5/10 on the CVSS scale. 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.. EPSS estimates a 8.40% chance of exploitation in the next 30 days.

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.

Metrics

CVSS 3.1

7.5/10

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

EPSS Probability

8.40%

94.3th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-400

Affected Software

Vendor	Product	Versions
Mitsubishielectric	Melsec Iq-R00 Firmware	>= 05, <= 19
Mitsubishielectric	Melsec Iq-R01 Firmware	>= 05, <= 19
Mitsubishielectric	Melsec Iq-R02 Firmware	>= 05, <= 19
Mitsubishielectric	Melsec Iq-R04 Firmware	>= 35, <= 51
Mitsubishielectric	Melsec Iq-R16 Firmware	>= 35, <= 51
Mitsubishielectric	Melsec Iq-R08 Firmware	>= 35, <= 51
Mitsubishielectric	Melsec Iq-R32 Firmware	>= 35, <= 51
Mitsubishielectric	Melsec Iq-R120 Firmware	>= 35, <= 51

References

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

Timeline

Published: Nov 16, 2020
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2020-5666?

How severe is CVE-2020-5666?

CVE-2020-5666 has a CVSS score of 7.5/10 (HIGH severity). The EPSS model estimates a 8.40% probability of exploitation in the next 30 days.

How do I fix CVE-2020-5666?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2020-5666?

Run a free Strix scan to check your systems for this vulnerability.

Scan your code now

Source: NVD / NIST