Honeywell Experion PKS

View CSAF

1. EXECUTIVE SUMMARY

• CVSS v3 9.4
• ATTENTION: Exploitable remotely/low attack complexity
• Vendor: Honeywell
• Equipment: Experion PKS
• Vulnerabilities: Use of Uninitialized Variable, Improper Restriction of Operations within the Bounds of a Memory Buffer, Sensitive Information in Resource Not Removed Before Reuse, Integer Underflow (Wrap or Wraparound), Deployment of Wrong Handler

2. RISK EVALUATION

Successful exploitation of these vulnerabilities could result in information exposure, denial of service, or remote code execution.

3. TECHNICAL DETAILS

3.1 AFFECTED PRODUCTS

Honeywell reports these vulnerabilities affect the following:

• Experion PKS: All releases prior to R520.2 TCU9 Hot Fix 1
• Experion PKS: All releases prior to R530 TCU3 Hot Fix 1

3.2 Vulnerability Overview

3.2.1 Use of Uninitialized Variable CWE-457

The Honeywell Experion PKS contains an uninitialized variable in the common Epic Platform Analyzer (EPA) communications. An attacker could potentially exploit this vulnerability, leading to communication channel manipulation, which results in a dereferencing of an uninitialized pointer leading to a denial of service.

CVE-2025-2520 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:N/I:N/A:H).

3.2.2 Improper Restriction of Operations within the Bounds of a Memory Buffer CWE-119

The Honeywell Experion PKS contains a memory buffer vulnerability in the component Control Data Access (CDA). An attacker could potentially exploit this vulnerability, leading to overread buffers, which could result in improper index validation against buffer borders, leading to remote code execution.

CVE-2025-2521 has been assigned to this vulnerability. A CVSS v3.1 base score of 8.6 has been calculated; the CVSS vector string is (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:H).

3.2.3 Sensitive Information in Resource Not Removed Before Reuse CWE-226

The Honeywell Experion PKS contains sensitive information in resource vulnerability in the component Control Data Access (CDA). An attacker could potentially exploit this vulnerability, leading to communication channel manipulation, which could result in buffer reuse, which may cause incorrect system behavior.

CVE-2025-2522 has been assigned to this vulnerability. A CVSS v3.1 base score of 6.5 has been calculated; the CVSS vector string is (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N).

3.2.4 Integer Underflow (Wrap or Wraparound) CWE-191

The Honeywell Experion PKS contains an integer underflow vulnerability in the component Control Data Access (CDA). An attacker could potentially exploit this vulnerability, leading to communication channel manipulation, which could result in a failure during subtraction, allowing remote code execution.

CVE-2025-2523 has been assigned to this vulnerability. A CVSS v3.1 base score of 9.4 has been calculated; the CVSS vector string is (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:H/A:H).

3.2.5 Deployment of Wrong Handler CWE-430

The Honeywell Experion PKS contains a deployment of wrong handler vulnerability in the component Control Data Access (CDA). An attacker could potentially exploit this vulnerability, leading to input data manipulation, which could result in incorrect handling of packets, leading to remote code execution.

CVE-2025-3946 has been assigned to this vulnerability. A CVSS v3.1 base score of 8.2 has been calculated; the CVSS vector string is (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:H).

3.2.6 Integer Underflow (Wrap or Wraparound) CWE-191

The Honeywell Experion PKS contains an integer underflow vulnerability in the component Control Data Access (CDA). An attacker could potentially exploit this vulnerability, leading to input data manipulation, which could result in improper integer data value checking during subtraction, leading to a denial of service.

CVE-2025-3947 has been assigned to this vulnerability. A CVSS v3.1 base score of 8.2 has been calculated; the CVSS vector string is (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:H).

3.3 BACKGROUND

• CRITICAL INFRASTRUCTURE SECTORS: Chemical, Critical Manufacturing, Energy, Healthcare and Public Health, Water and Wastewater Systems
• COUNTRIES/AREAS DEPLOYED: Worldwide
• COMPANY HEADQUARTERS LOCATION: United States

3.4 RESEARCHER

Positive Technologies reported these vulnerabilities to Honeywell.

4. MITIGATIONS

Honeywell recommends updating Experion PKS R520.2 TCU9 Hot Fix 1 or R530 TCU3 Hot Fix 1. For more information, see the Security Notice.

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

• Ensure the least-privilege user principle is followed.
• 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 these vulnerabilities has been reported to CISA at this time.

5. UPDATE HISTORY

• July 24, 2025: Initial Republication of Honeywell security notice.

• Honeywell