CVE-2025-11783 is a stack-based buffer overflow vulnerability identified in Circutor's SGE-PLC1000 and SGE-PLC50 programmable logic controllers (PLCs), specifically in firmware version 9.0.2. The vulnerability arises in the AddEvent() function, which processes user-supplied username input. This input is copied into a fixed-size buffer of 48 bytes without proper boundary checking, leading to a classic stack buffer overflow condition (CWE-121). Exploiting this flaw can cause memory corruption, potentially allowing an attacker to execute arbitrary code remotely on the affected device. The vulnerability requires adjacent network access (AV:A), meaning the attacker must be on the same local network segment or have network proximity, but does not require user interaction (UI:N) or elevated privileges beyond low privileges (PR:L). The vulnerability impacts confidentiality, integrity, and availability with high vector components for confidentiality and availability (VC:H, VA:H). The scope is high (SC:H), indicating that exploitation could affect resources beyond the vulnerable component. The vulnerability was published on December 2, 2025, with no known exploits in the wild yet. Circutor PLCs are commonly used in industrial control systems, including energy management and automation, making this vulnerability particularly critical for operational technology environments. The lack of available patches at the time of publication increases the urgency for mitigation through network controls and monitoring.

For European organizations, especially those operating critical infrastructure such as energy grids, manufacturing plants, and industrial automation systems, this vulnerability poses a significant risk. Successful exploitation could lead to unauthorized remote code execution on PLC devices, potentially disrupting industrial processes, causing equipment malfunction, or enabling further lateral movement within operational technology networks. This could result in operational downtime, safety hazards, and data breaches affecting sensitive industrial control information. Given the high availability and integrity impact, organizations may face severe operational and financial consequences. The requirement for adjacent network access somewhat limits the attack surface but does not eliminate risk, especially in environments where network segmentation is weak or remote access solutions are improperly configured. The absence of known exploits currently provides a window for proactive defense but also underscores the need for rapid response once exploit code becomes available.

1. Immediately implement strict network segmentation to isolate Circutor PLC devices from general IT networks and restrict access to trusted management stations only. 2. Employ access control lists (ACLs) and firewall rules to limit network traffic to and from the affected devices, ensuring only authorized systems can communicate with them. 3. Monitor network traffic for anomalous activity targeting the AddEvent() function or unusual username input patterns that could indicate exploitation attempts. 4. Coordinate with Circutor or authorized vendors to obtain and apply firmware updates or patches as soon as they are released. 5. If patches are not yet available, consider temporary mitigations such as disabling or restricting the vulnerable AddEvent() functionality if feasible. 6. Conduct thorough audits of existing PLC deployments to identify all devices running vulnerable firmware versions. 7. Implement strong authentication and logging mechanisms on management interfaces to detect and prevent unauthorized access. 8. Train operational technology personnel on this vulnerability and the importance of maintaining strict network hygiene and monitoring.