Mitsubishi Electric MELSEC iQ-F Series CPU Module

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1. EXECUTIVE SUMMARY

• CVSS v4 8.7
• ATTENTION: Exploitable remotely/low attack complexity
• Vendor: Mitsubishi Electric
• Equipment: MELSEC iQ-F Series CPU module
• Vulnerability: Cleartext Transmission of Sensitive Information

2. RISK EVALUATION

Successful exploitation of this vulnerability could allow an attacker the ability to obtain credential information by intercepting SLMP communication messages, and read or write the device values of the product by using the obtained credential information. In addition, the attacker may be able to stop the operations of programs.

3. TECHNICAL DETAILS

3.1 AFFECTED PRODUCTS

Mitsubishi Electric reports the following versions of MELSEC iQ-F Series CPU module are affected:

• MELSEC iQ-F Series FX5U-32MT/ES: All versions
• MELSEC iQ-F Series FX5U-32MT/DS: All versions
• MELSEC iQ-F Series FX5U-32MT/ESS: All versions
• MELSEC iQ-F Series FX5U-32MT/DSS: All versions
• MELSEC iQ-F Series FX5U-64MT/ES: All versions
• MELSEC iQ-F Series FX5U-64MT/DS: All versions
• MELSEC iQ-F Series FX5U-64MT/ESS: All versions
• MELSEC iQ-F Series FX5U-64MT/DSS: All versions
• MELSEC iQ-F Series FX5U-80MT/ES: All versions
• MELSEC iQ-F Series FX5U-80MT/DS: All versions
• MELSEC iQ-F Series FX5U-80MT/ESS: All versions
• MELSEC iQ-F Series FX5U-80MT/DSS: All versions
• MELSEC iQ-F Series FX5U-32MR/ES: All versions
• MELSEC iQ-F Series FX5U-32MR/DS: All versions
• MELSEC iQ-F Series FX5U-64MR/ES: All versions
• MELSEC iQ-F Series FX5U-64MR/DS: All versions
• MELSEC iQ-F Series FX5U-80MR/ES: All versions
• MELSEC iQ-F Series FX5U-80MR/DS: All versions
• MELSEC iQ-F Series FX5UC-32MT/D: All versions
• MELSEC iQ-F Series FX5UC-32MT/DSS: All versions
• MELSEC iQ-F Series FX5UC-64MT/D: All versions
• MELSEC iQ-F Series FX5UC-64MT/DSS: All versions
• MELSEC iQ-F Series FX5UC-96MT/D: All versions
• MELSEC iQ-F Series FX5UC-96MT/DSS: All versions
• MELSEC iQ-F Series FX5UC-32MT/DS-TS: All versions
• MELSEC iQ-F Series FX5UC-32MT/DSS-TS: All versions
• MELSEC iQ-F Series FX5UC-32MR/DS-TS: All versions
• MELSEC iQ-F Series FX5UJ-24MT/ES: All versions
• MELSEC iQ-F Series FX5UJ-24MT/DS: All versions
• MELSEC iQ-F Series FX5UJ-24MT/ESS: All versions
• MELSEC iQ-F Series FX5UJ-24MT/DSS: All versions
• MELSEC iQ-F Series FX5UJ-40MT/ES: All versions
• MELSEC iQ-F Series FX5UJ-40MT/DS: All versions
• MELSEC iQ-F Series FX5UJ-40MT/ESS: All versions
• MELSEC iQ-F Series FX5UJ-40MT/DSS: All versions
• MELSEC iQ-F Series FX5UJ-60MT/ES: All versions
• MELSEC iQ-F Series FX5UJ-60MT/DS: All versions
• MELSEC iQ-F Series FX5UJ-60MT/ESS: All versions
• MELSEC iQ-F Series FX5UJ-60MT/DSS: All versions
• MELSEC iQ-F Series FX5UJ-24MR/ES: All versions
• MELSEC iQ-F Series FX5UJ-24MR/DS: All versions
• MELSEC iQ-F Series FX5UJ-40MR/ES: All versions
• MELSEC iQ-F Series FX5UJ-40MR/DS: All versions
• MELSEC iQ-F Series FX5UJ-60MR/ES: All versions
• MELSEC iQ-F Series FX5UJ-60MR/DS: All versions
• MELSEC iQ-F Series FX5UJ-24MT/ES-A: All versions
• MELSEC iQ-F Series FX5UJ-24MR/ES-A: All versions
• MELSEC iQ-F Series FX5UJ-40MT/ES-A: All versions
• MELSEC iQ-F Series FX5UJ-40MR/ES-A: All versions
• MELSEC iQ-F Series FX5UJ-60MT/ES-A: All versions
• MELSEC iQ-F Series FX5UJ-60MR/ES-A: All versions
• MELSEC iQ-F Series FX5S-30MT/ES: All versions
• MELSEC iQ-F Series FX5S-30MT/DS: All versions
• MELSEC iQ-F Series FX5S-30MT/ESS: All versions
• MELSEC iQ-F Series FX5S-30MT/DSS: All versions
• MELSEC iQ-F Series FX5S-40MT/ES: All versions
• MELSEC iQ-F Series FX5S-40MT/DS: All versions
• MELSEC iQ-F Series FX5S-40MT/ESS: All versions
• MELSEC iQ-F Series FX5S-40MT/DSS: All versions
• MELSEC iQ-F Series FX5S-60MT/ES: All versions
• MELSEC iQ-F Series FX5S-60MT/DS: All versions
• MELSEC iQ-F Series FX5S-60MT/ESS: All versions
• MELSEC iQ-F Series FX5S-60MT/DSS: All versions
• MELSEC iQ-F Series FX5S-80MT/ES: All versions
• MELSEC iQ-F Series FX5S-80MT/DS: All versions
• MELSEC iQ-F Series FX5S-80MT/ESS: All versions
• MELSEC iQ-F Series FX5S-80MT/DSS: All versions
• MELSEC iQ-F Series FX5S-30MR/ES: All versions
• MELSEC iQ-F Series FX5S-30MR/DS: All versions
• MELSEC iQ-F Series FX5S-40MR/ES: All versions
• MELSEC iQ-F Series FX5S-40MR/DS: All versions
• MELSEC iQ-F Series FX5S-60MR/ES: All versions
• MELSEC iQ-F Series FX5S-60MR/DS: All versions
• MELSEC iQ-F Series FX5S-80MR/ES: All versions
• MELSEC iQ-F Series FX5S-80MR/DS: All versions

3.2 VULNERABILITY OVERVIEW

3.2.1 CLEARTEXT TRANSMISSION OF SENSITIVE INFORMATION CWE-319

An information disclosure vulnerability exists in MELSEC iQ-F series CPU module due to cleartext transmission of sensitive information. An attacker may obtain credential information by intercepting SLMP communication messages and using the obtained credentials to read or write the device values. Additionally, the attacker may be able to stop the operation of programs.

CVE-2025-7731 has been assigned to this vulnerability. A CVSS v3.1 base score of 7.5 has been calculated; the CVSS vector string is (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N).

A CVSS v4 score has also been calculated for CVE-2025-7731. A base score of 8.7 has been calculated; the CVSS vector string is (CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N).

3.3 BACKGROUND

• CRITICAL INFRASTRUCTURE SECTORS: Critical Manufacturing
• COUNTRIES/AREAS DEPLOYED: Worldwide
• COMPANY HEADQUARTERS LOCATION: Japan

3.4 RESEARCHER

Thai Do, Minh Pham, Quan Le and Loc Nguyen of Unit 515, OPSWAT reported this vulnerability to Mitsubishi Electric.

4. MITIGATIONS

Mitsubishi Electric Corporation advises there are no plans to release a fixed version. Mitsubishi Electric recommends users take the following mitigation measures to minimize the risk of exploiting this vulnerability:

• Use a virtual private network (VPN) or similar to encrypt SLMP communication.
• Restrict physical access to the LAN connected by the affected products.

Mitsubishi Electric Corporation recommends users contact their local Mitsubishi Electric representative with questions.

For more information, see Mitsubishi Electric's security advisory.

CISA recommends users take defensive measures to minimize the risk of exploitation of this vulnerability, such as:

• Minimize network exposure for all control system devices and/or systems, ensuring they are not accessible from the internet.
• Locate control system networks and remote devices behind firewalls and isolating them from business networks.

CISA reminds organizations to perform proper impact analysis and risk assessment prior to deploying defensive measures.

CISA also provides a section for control systems security recommended practices on the ICS webpage on cisa.gov/ics. Several CISA products detailing cyber defense best practices are available for reading and download, including Improving Industrial Control Systems Cybersecurity with Defense-in-Depth Strategies.

CISA encourages organizations to implement recommended cybersecurity strategies for proactive defense of ICS assets.

Additional mitigation guidance and recommended practices are publicly available on the ICS webpage at cisa.gov/ics in the technical information paper, ICS-TIP-12-146-01B--Targeted Cyber Intrusion Detection and Mitigation Strategies.

Organizations observing suspected malicious activity should follow established internal procedures and report findings to CISA for tracking and correlation against other incidents.

No known public exploitation specifically targeting this vulnerability has been reported to CISA at this time.

5. UPDATE HISTORY

• August 28, 2025: Initial Republication of Mitsubishi Electric 2025-012

• Mitsubishi Electric