CVE-2025-11788: Circutor SGE-PLC1000 Buffer Overflow Flaw

CVE-2025-11788 Overview

A heap-based buffer overflow vulnerability has been identified in Circutor SGE-PLC1000 and SGE-PLC50 programmable logic controllers running firmware version 9.0.2. The vulnerability exists in the ShowSupervisorParameters() function, where unlimited user input is copied to a fixed-size buffer via the unsafe sprintf() function. The GetParameter(meter) function retrieves user input which is directly incorporated into a buffer without proper size validation, allowing an attacker to provide an excessively large input for the meter parameter and trigger a heap overflow condition.

This vulnerability affects industrial control systems (ICS) and SCADA environments, making it particularly concerning for critical infrastructure deployments. The network-accessible attack vector combined with the high impact on confidentiality and availability makes this a significant security risk for organizations using these Circutor PLC devices.

Critical Impact

Network-accessible heap-based buffer overflow in industrial PLC firmware enables potential remote code execution and denial of service attacks against critical infrastructure systems with a CVSS score of 8.5 (HIGH).

Affected Products

• Circutor SGE-PLC1000 Firmware version 9.0.2
• Circutor SGE-PLC1000 Hardware
• Circutor SGE-PLC50 Firmware version 9.0.2
• Circutor SGE-PLC50 Hardware

Discovery Timeline

• 2025-12-02 - CVE-2025-11788 published to NVD
• 2025-12-03 - Last updated in NVD database

Technical Details for CVE-2025-11788

Vulnerability Analysis

This vulnerability is classified as CWE-122 (Heap-based Buffer Overflow). The flaw resides in the firmware's handling of the meter parameter within the ShowSupervisorParameters() function. When processing HTTP requests or similar input mechanisms, the function calls GetParameter(meter) to retrieve user-supplied data. This data is then passed to sprintf() without any bounds checking, resulting in a classic heap-based buffer overflow condition.

The CVSS 4.0 vector string CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:N/VA:H/SC:H/SI:N/SA:H indicates:

• Attack Vector: Network (remotely exploitable)
• Attack Complexity: Low (no specialized conditions required)
• Privileges Required: Low (some authentication needed)
• User Interaction: None required
• Confidentiality Impact: High (both vulnerable and subsequent systems)
• Availability Impact: High (potential for denial of service)

The EPSS (Exploit Prediction Scoring System) score of 0.047% places this vulnerability at the 14.71st percentile, indicating a relatively low probability of exploitation in the wild at this time.

Root Cause

The root cause of this vulnerability is improper input validation combined with the use of unsafe string handling functions. The GetParameter(meter) function accepts arbitrary user input without implementing any length restrictions. This unsanitized input is subsequently processed by sprintf(), which copies data to a fixed-size heap buffer without checking whether the source data exceeds the destination buffer's capacity.

The use of sprintf() instead of safer alternatives like snprintf() is a common programming error that leads to buffer overflow vulnerabilities. In embedded systems like PLCs, such vulnerabilities are particularly dangerous due to the limited security controls and the critical nature of the systems they manage.

Attack Vector

An attacker with low-level privileges can exploit this vulnerability remotely over the network by sending a crafted request containing an oversized meter parameter value. The attack does not require any user interaction and can be executed with relatively low complexity.

The exploitation flow involves:

1. Establishing a network connection to the vulnerable PLC device
2. Sending a request that includes an excessively long value for the meter parameter
3. The GetParameter(meter) function retrieves this malicious input
4. The ShowSupervisorParameters() function passes the data to sprintf() without validation
5. The oversized data overflows the heap buffer, potentially corrupting adjacent memory structures

Successful exploitation could allow an attacker to achieve denial of service by crashing the PLC, potentially read sensitive information from memory, or in some cases achieve code execution depending on the heap layout and exploitation technique employed.

Detection Methods for CVE-2025-11788

Indicators of Compromise

• Abnormally long HTTP request parameters or inputs targeting the meter parameter
• PLC device crashes or unexpected reboots without clear operational cause
• Memory corruption errors or segmentation faults in device logs
• Unusual network traffic patterns to PLC management interfaces
• Attempts to access supervisor parameter endpoints with oversized payloads

Detection Strategies

Organizations should implement network-based detection to identify exploitation attempts. Monitor for HTTP requests containing abnormally long parameter values directed at Circutor PLC devices. Intrusion detection systems (IDS) and intrusion prevention systems (IPS) can be configured with signatures to detect buffer overflow attack patterns targeting these devices.

SentinelOne Singularity provides comprehensive protection for industrial control system environments through behavioral analysis and anomaly detection. The platform can identify exploitation attempts targeting ICS devices and provide real-time visibility into threats affecting operational technology networks.

Implement deep packet inspection at network boundaries to analyze traffic destined for PLC management interfaces. Consider deploying honeypots mimicking vulnerable Circutor devices to detect active reconnaissance and exploitation attempts.

Monitoring Recommendations

Enable verbose logging on all Circutor PLC devices and forward logs to a centralized SIEM solution for analysis. Monitor for authentication anomalies and unusual access patterns to supervisor functions. Implement network segmentation to isolate PLC devices and monitor all traffic crossing segmentation boundaries. Deploy network traffic analysis tools to baseline normal communication patterns and alert on deviations that may indicate exploitation attempts.

How to Mitigate CVE-2025-11788

Immediate Actions Required

• Isolate affected Circutor SGE-PLC1000 and SGE-PLC50 devices from untrusted networks immediately
• Implement strict network access controls limiting connectivity to only authorized management stations
• Deploy web application firewalls (WAF) or IPS rules to filter requests with oversized meter parameters
• Enable additional logging and monitoring for affected devices
• Review access control lists and ensure principle of least privilege is enforced

Patch Information

Consult the INCIBE-CERT security advisory at https://www.incibe.es/en/incibe-cert/notices/aviso-sci/multiple-vulnerabilities-circutor-products-0 for the latest patch availability and vendor guidance. Contact Circutor directly to obtain firmware updates that address this vulnerability. Organizations should prioritize applying security patches as soon as they become available from the vendor.

Workarounds

If immediate patching is not possible, organizations should implement compensating controls to reduce the risk of exploitation. Network segmentation is critical—place all affected PLCs in isolated network segments with strict firewall rules limiting inbound connections. Implement authentication and access control at the network layer to ensure only authorized personnel can communicate with PLC devices.

Consider deploying a reverse proxy or application-level gateway in front of PLC web interfaces to perform input validation and reject requests with excessively long parameters. This can serve as a temporary mitigation until vendor patches are applied.

# Example iptables rules to restrict PLC access to authorized management stations only
iptables -A INPUT -p tcp -d <PLC_IP> --dport 80 -s <AUTHORIZED_MGMT_IP> -j ACCEPT
iptables -A INPUT -p tcp -d <PLC_IP> --dport 443 -s <AUTHORIZED_MGMT_IP> -j ACCEPT
iptables -A INPUT -p tcp -d <PLC_IP> --dport 80 -j DROP
iptables -A INPUT -p tcp -d <PLC_IP> --dport 443 -j DROP