1. EXECUTIVE SUMMARY
- CVSS v4 6.1
- ATTENTION: Low attack complexity
- Vendor: OpenPLC_V3
- Equipment: OpenPLC_V3
- Vulnerability: Reliance on Undefined, Unspecified, or Implementation-Defined Behavior
2. RISK EVALUATION
Successful exploitation of this vulnerability could cause a denial of service, making the PLC runtime process crash.
3. TECHNICAL DETAILS
3.1 AFFECTED PRODUCTS
The following versions of OpenPLC_V3 are affected:
- OpenPLC_V3: Versions prior to pull request #292
3.2 VULNERABILITY OVERVIEW
3.2.1 RELIANCE ON UNDEFINED, UNSPECIFIED, OR IMPLEMENTATION-DEFINED BEHAVIOR CWE-758
OpenPLC_V3 has a vulnerability in the enipThread function that occurs due to the lack of a return value. This leads to a crash when the server loop ends and execution hits an illegal ud2 instruction. This issue can be triggered remotely without authentication by starting the same server multiple times or if the server exits unexpectedly. The vulnerability allows an attacker to cause a Denial of Service (DoS) against the PLC runtime, stopping any PC started remotely without authentication. This results in the PLC process crashing and halting all automation or control logic managed by OpenPLC.
CVE-2025-54811 has been assigned to this vulnerability. A CVSS v3.1 base score of 7.1 has been calculated; the CVSS vector string is (AV:L/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H).
A CVSS v4 score has also been calculated for CVE-2025-54811. A base score of 6.1 has been calculated; the CVSS vector string is (AV:L/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:N/SC:N/SI:N/SA:H).
3.3 BACKGROUND
- CRITICAL INFRASTRUCTURE SECTORS: Critical Manufacturing, Energy, Transportation Systems, Water and Wastewater Systems
- COUNTRIES/AREAS DEPLOYED: Worldwide
- COMPANY HEADQUARTERS LOCATION: United States
3.4 RESEARCHER
Renato Garreton of TryHackMe reported this vulnerability to CISA.
4. MITIGATIONS
Pull request #292 resolves this issue. Users are advised to update OpenPLC_V3 to pull request #292 or later from the main GitHub repository.
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. This vulnerability is not exploitable remotely.
5. UPDATE HISTORY
- September 30, 2025: Initial Publication
