CVE-2024-39590 is a vulnerability identified in OpenPLC_v3, an open-source industrial control system platform. The flaw resides in the EtherNet/IP protocol parser, specifically in the Protected_Logical_Write_Reply function, where multiple invalid pointer dereferences occur due to incorrect type conversion or casting (CWE-704). This vulnerability allows an unauthenticated remote attacker to send a series of specially crafted EtherNet/IP requests that trigger these invalid pointer dereferences, causing the OpenPLC runtime to crash or become unresponsive, resulting in a denial of service (DoS) condition. The vulnerability is exploitable over the network without requiring any privileges or user interaction, making it relatively easy to exploit in environments where OpenPLC is exposed. The CVSS v3.1 score of 7.5 reflects the high impact on availability with no impact on confidentiality or integrity. The vulnerability affects a specific commit/version of OpenPLC_v3 (16bf8bac1a36d95b73e7b8722d0edb8b9c5bb56a). Although no public exploits are known at this time, the nature of the flaw and the critical role of OpenPLC in industrial automation systems make this a significant threat. The root cause is improper handling of data types during the parsing of EtherNet/IP protocol messages, leading to unsafe memory operations and crashes. This vulnerability highlights the importance of robust input validation and type safety in industrial protocol implementations.

The primary impact of CVE-2024-39590 is denial of service, which can disrupt industrial control processes managed by OpenPLC. For European organizations, especially those in manufacturing, energy, utilities, and critical infrastructure sectors that rely on OpenPLC for automation, this can lead to operational downtime, safety risks, and financial losses. The vulnerability does not compromise data confidentiality or integrity but affects system availability, which is critical in industrial environments. Disruption of control systems can halt production lines or cause unsafe conditions if safety interlocks or monitoring systems fail. Given the network-exploitable nature without authentication, attackers could target exposed OpenPLC instances remotely, increasing the risk of widespread disruption. The lack of known exploits currently limits immediate risk, but the potential for future exploitation remains. Organizations with insufficient network segmentation or exposure of EtherNet/IP services to untrusted networks are at higher risk. The impact is amplified in sectors with stringent uptime requirements and regulatory compliance obligations, such as energy grids and manufacturing plants.

1. Apply patches or updates from the OpenPLC project as soon as they become available to address the pointer dereference issues. 2. Until patches are released, implement strict network segmentation to isolate OpenPLC systems from untrusted networks, limiting access to EtherNet/IP ports only to trusted devices. 3. Deploy network-level filtering and intrusion detection systems to monitor and block malformed or suspicious EtherNet/IP traffic targeting OpenPLC devices. 4. Conduct regular security assessments and penetration tests focusing on industrial protocol implementations to identify similar vulnerabilities. 5. Enforce strict access controls and minimize exposure of OpenPLC runtime services to the internet or large internal networks. 6. Maintain up-to-date inventories of OpenPLC deployments and versions to prioritize remediation efforts. 7. Educate operational technology (OT) staff on the risks of malformed protocol messages and encourage monitoring for unusual system crashes or network traffic patterns. 8. Consider implementing application-layer firewalls or protocol-aware gateways that can validate EtherNet/IP message integrity before forwarding to OpenPLC devices.