Uncontrolled resource consumption vulnerability in MELSEC iQ-R Series CPU Modules (R00/01/02CPU Firmware versions from '05' to '19' and R04…

published 2020-11-16 5 y ago modified 2026-06-17 4 mo ago also EUVD-2020-26827

cvss: 7.5; version 3.1, NVD
cisa kev: Not listed; not in CISA's catalog
epss: 8.8%; EPSS 8.8% chance of exploitation in 30 days, percentile 95%
public exploits: 0; none known

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.

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

cisa ICSA-20-317-01 updated 2020-11-12 cvss 6.8

Mitsubishi Electric MELSEC iQ-R Series

Mitsubishi Electric MELSEC iQ-R series CPU module products R00/01/02 CPU >= 05, <=10 Mitsubishi Electric MELSEC iQ-R series CPU module products R04/08/16/32/120(EN) CPU >= 35, <= 51
affected: mitigation “R00/01/02CPU: firmware Versions 20 or later” mitsubishielectric.com

From CISA ICS and IT advisories (CSAF, https://github.com/cisagov/CSAF), a U.S. Government work; changed: reduced to products, statuses and remediations. CISA notification · csaf

Exploit prediction

8.75% chance of exploitation in the next 30 days, higher than 95% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by	version	score	vector
NVD	3.1	7.5	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
NVD	2.0	7.1	AV:N/AC:M/Au:N/C:N/I:N/A:C

Affected products

Mitsubishi Electric Corporation MELSEC iQ-R Series CPU Modules

Classification

Weakness

CWE-400 Uncontrolled Resource Consumption

References

mitsubishielectric.com /en/psirt/vulnerability/pdf/2020-015_en.pdf
mitigation, vendor-advisory
jvn.jp /jp/JVN44764844/index.html
third-party-advisory
jvn.jp /en/jp/JVN44764844/index.html
third-party-advisory
us-cert.cisa.gov /ics/advisories/icsa-20-317-01
third-party-advisory, us-government-resource

Sources

CVE List CVE-2020-5666
NVD CVE-2020-5666

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

Summary