CVE-2020-5656

Name: CVE-2020-5656
Creator: NVD / NIST
Published: 2020-11-02T21:15:33.96+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

CRITICALCVSS 9.8/10EPSS 2.93%

Last modified Jun 17, 2026

CVE-2020-5656 is a critical-severity vulnerability rated 9.8/10 on the CVSS scale. Improper access control vulnerability in TCP/IP function included in the firmware of MELSEC iQ-R series (RJ71EIP91 EtherNet/IP Network Interface Module First 2 digits of serial number are '02' or before, RJ71PN92 PROFINET IO Controller Module First 2 digits of serial number are '01' or before, RD81DL96 High Speed Data Logger Module First 2 digits of serial number are '08' or before, RD81MES96N MES Interface Module First 2 digits of serial number are '04' or before, and RD81OPC96 OPC UA Server Module First 2 digits of serial number are '04' or before) allows a remote unauthenticated attacker to stop the network functions of the products or execute a malicious program via a specially crafted packet.. EPSS estimates a 2.93% chance of exploitation in the next 30 days.

Description

Improper access control vulnerability in TCP/IP function included in the firmware of MELSEC iQ-R series (RJ71EIP91 EtherNet/IP Network Interface Module First 2 digits of serial number are '02' or before, RJ71PN92 PROFINET IO Controller Module First 2 digits of serial number are '01' or before, RD81DL96 High Speed Data Logger Module First 2 digits of serial number are '08' or before, RD81MES96N MES Interface Module First 2 digits of serial number are '04' or before, and RD81OPC96 OPC UA Server Module First 2 digits of serial number are '04' or before) allows a remote unauthenticated attacker to stop the network functions of the products or execute a malicious program via a specially crafted packet.

Metrics

CVSS 3.1

9.8/10

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

EPSS Probability

2.93%

85.3th percentile

Probability of exploitation in the next 30 days. Learn more

Affected Software

Vendor	Product	Versions
Mitsubishielectric	Melsec Iq-Rj71eip91 Firmware	All versions
Mitsubishielectric	Melsec Iq-Rj71pn92 Firmware	All versions
Mitsubishielectric	Melsec Iq-Rd81dl96 Firmware	All versions
Mitsubishielectric	Melsec Iq-Rd81mes96n Firmware	All versions
Mitsubishielectric	Melsec Iq-Rd81opc96 Firmware	All versions

References

https://jvn.jp/vu/JVNVU92513419/index.htmlThird Party Advisory
https://www.mitsubishielectric.co.jp/psirt/vulnerability/pdf/2020-012.pdfVendor Advisory
https://www.mitsubishielectric.com/en/psirt/vulnerability/pdf/2020-012_en.pdfVendor Advisory
https://jvn.jp/vu/JVNVU92513419/index.htmlThird Party Advisory
https://www.mitsubishielectric.co.jp/psirt/vulnerability/pdf/2020-012.pdfVendor Advisory
https://www.mitsubishielectric.com/en/psirt/vulnerability/pdf/2020-012_en.pdfVendor Advisory

Timeline

Published: Nov 2, 2020
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2020-5656?

How severe is CVE-2020-5656?

CVE-2020-5656 has a CVSS score of 9.8/10 (CRITICAL severity). The EPSS model estimates a 2.93% probability of exploitation in the next 30 days.

How do I fix CVE-2020-5656?

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-2020-5656?

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

Scan your code now

Source: NVD / NIST