CVE-2024-50956 identifies a buffer overflow vulnerability in the RecvSocketData function of Inovance HCPLC series PLCs, specifically models HCPLC_AM401-CPU1608TPTN (version 21.38.0.0), HCPLC_AM402-CPU1608TPTN (41.38.0.0), and HCPLC_AM403-CPU1608TN (81.38.0.0). The flaw lies in improper handling of incoming Modbus protocol messages, where crafted packets can overflow a buffer, leading to memory corruption. This can cause the affected device to crash (denial of service) or potentially allow an attacker to execute arbitrary code remotely. The vulnerability is exploitable over the network without requiring authentication or user interaction, increasing its risk profile in exposed environments. The weakness is classified under CWE-120 (classic buffer overflow). The CVSS v3.1 base score is 6.5, reflecting a medium severity due to network attack vector, low attack complexity, no privileges required, no user interaction, and impact limited to availability. No patches or mitigations have been officially released at the time of publication, and no known exploits are in the wild. Given the critical role of these PLCs in industrial automation, exploitation could disrupt manufacturing or process control operations.

The primary impact of this vulnerability is on the availability and potentially the integrity of industrial control systems using the affected Inovance HCPLC models. Successful exploitation can cause device crashes, leading to denial of service conditions that interrupt industrial processes, potentially causing production downtime and safety risks. In a worst-case scenario, arbitrary code execution could allow attackers to take control of the PLC, manipulate control logic, or pivot to other parts of the network, compromising operational integrity. This risk is heightened in environments where these PLCs are exposed to untrusted networks or insufficiently segmented industrial networks. The lack of authentication requirements and ease of exploitation over the network increase the threat to critical infrastructure sectors such as manufacturing, energy, and utilities that rely on these controllers.

Until official patches are available, organizations should implement strict network segmentation to isolate affected PLCs from untrusted networks and limit Modbus traffic to trusted sources only. Deploy network-level intrusion detection and prevention systems (IDS/IPS) with signatures or anomaly detection for unusual Modbus traffic patterns. Disable or restrict Modbus services on PLCs if not required. Regularly monitor PLC logs and network traffic for signs of malformed packets or repeated connection attempts. Employ strict access controls and VPNs for remote access to industrial networks. Coordinate with Inovance support channels for updates and apply patches immediately upon release. Conduct thorough risk assessments and incident response planning specific to industrial control system environments.