1. EXECUTIVE SUMMARY

CVSS v4 9.3
ATTENTION: Exploitable remotely/low attack complexity
Vendor: Johnson Controls Inc.
Equipment: iSTAR Configuration Utility (ICU)
Vulnerability: Stack-based Buffer Overflow

2. RISK EVALUATION

Successful exploitation of this vulnerability may allow an attacker to execute arbitrary code.

3. TECHNICAL DETAILS

3.1 AFFECTED PRODUCTS

Johnson Controls reports the following versions of ICU are affected:

ICU: Versions prior to 6.9.5

3.2 VULNERABILITY OVERVIEW

3.2.1 STACK-BASED BUFFER OVERFLOW CWE-121

Under certain circumstances, the ICU tool can have a buffer overflow issue.

CVE-2025-26382 has been assigned to this vulnerability. A CVSS v3.1 base score of 9.8 has been calculated; the CVSS vector string is (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H).

A CVSS v4 score has also been calculated for CVE-2025-26382. A base score of 9.3 has been calculated; the CVSS vector string is (CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N).

3.3 BACKGROUND

CRITICAL INFRASTRUCTURE SECTORS: Critical Manufacturing, Commercial Facilities, Government Services and Facilities, Transportation Systems, Energy
COUNTRIES/AREAS DEPLOYED: Worldwide
COMPANY HEADQUARTERS LOCATION: Ireland

3.4 RESEARCHER

Reid Wightman of Dragos reported this vulnerability to Johnson Controls, Inc.

4. MITIGATIONS

Johnson Controls recommends users upgrade ICU to Version 6.9.5 or greater.

For more detailed mitigation instructions, please see Johnson Controls Product Security Advisory JCI-PSA-2025-04.

Aligning with CISA recommendations, Johnson Controls recommends taking steps to minimize risks to all building automation systems.

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.
When remote access is required, use more secure methods, such as virtual private networks (VPNs), recognizing VPNs may have vulnerabilities and should be updated to the most current version available. Also recognize VPN is only as secure as the connected devices.

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

April 24, 2025: Initial Republication of Johnson Controls JCI-PSA-2025-04