CVE-2025-11785: Circutor SGE-PLC Buffer Overflow Flaw

CVE-2025-11785 Overview

CVE-2025-11785 is a stack-based buffer overflow vulnerability affecting Circutor SGE-PLC1000 and SGE-PLC50 industrial programmable logic controllers running firmware version 9.0.2. The vulnerability exists in the ShowMeterPasswords() function, where unlimited user input is copied to a fixed-size buffer via sprintf() without proper size validation. The GetParameter(meter) function retrieves user-supplied input that is directly incorporated into a buffer, allowing an attacker to provide an excessively large input for the meter parameter and trigger a buffer overflow condition.

This vulnerability is classified as HIGH severity with a CVSS 4.0 score of 8.5, indicating significant risk to affected industrial control systems. The attack vector requires adjacent network access, meaning an attacker must be on the same network segment as the vulnerable device.

Critical Impact

Attackers on adjacent networks can exploit this stack-based buffer overflow to potentially achieve code execution on industrial PLCs, compromising operational technology environments and critical infrastructure systems.

Affected Products

• Circutor SGE-PLC1000 Firmware v9.0.2
• Circutor SGE-PLC1000 Hardware
• Circutor SGE-PLC50 Firmware v9.0.2
• Circutor SGE-PLC50 Hardware

Discovery Timeline

• 2025-12-02 - CVE-2025-11785 published to NVD
• 2025-12-03 - Last updated in NVD database

Technical Details for CVE-2025-11785

Vulnerability Analysis

The vulnerability is classified under CWE-121 (Stack-based Buffer Overflow), a memory corruption flaw that occurs when a program writes data beyond the boundaries of a stack-allocated buffer. In this case, the ShowMeterPasswords() function uses the unsafe sprintf() function to copy user-controlled data into a fixed-size stack buffer without implementing any bounds checking.

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

• Attack Vector (AV:A): Adjacent network access required
• Attack Complexity (AC:L): Low complexity to exploit
• Privileges Required (PR:L): Low-level privileges needed
• User Interaction (UI:N): No user interaction required
• Confidentiality Impact (VC:H): High impact on vulnerable system confidentiality
• Availability Impact (VA:H): High impact on system availability
• Subsequent System Impact: High confidentiality and availability impact on downstream systems

The EPSS (Exploit Prediction Scoring System) probability is 0.063% (19.6th percentile), suggesting relatively low likelihood of exploitation in the wild currently.

Root Cause

The root cause is the use of the unsafe sprintf() function combined with inadequate input validation. When the GetParameter(meter) function retrieves user input from the meter parameter, this data is passed directly to sprintf() without any length checks. Since the destination buffer has a fixed size allocated on the stack, providing input that exceeds this buffer size results in stack memory corruption.

This is a classic example of insecure coding practices in embedded systems, where memory-safe alternatives like snprintf() should be used instead of sprintf().

Attack Vector

An attacker with adjacent network access to the vulnerable Circutor PLC device can craft a malicious request containing an oversized value for the meter parameter. When the ShowMeterPasswords() function processes this request, the sprintf() function copies the attacker-controlled data past the buffer boundary, corrupting adjacent stack memory.

Depending on the stack layout and available protections (or lack thereof) on the embedded device, successful exploitation could lead to:

• Overwriting the saved return address to redirect execution flow
• Overwriting local variables to manipulate program logic
• Denial of service through stack corruption causing system crash
• Potential remote code execution if the attacker can control the instruction pointer

The attack requires low privileges and no user interaction, making it relatively straightforward to exploit once network access is obtained.

Detection Methods for CVE-2025-11785

Indicators of Compromise

• Unusual or malformed HTTP/network requests to PLC web interface containing extremely long meter parameter values
• Unexpected device reboots or crashes of Circutor SGE-PLC1000 or SGE-PLC50 controllers
• Anomalous memory access patterns or segmentation faults in PLC logs
• Network traffic from unexpected sources targeting the PLC management interface

Detection Strategies

Network-Based Detection:
Monitor network traffic to Circutor PLC devices for requests containing abnormally large parameter values. Implement intrusion detection rules that flag HTTP requests with meter parameters exceeding normal operational lengths.

Host-Based Detection:
If the PLC supports logging, monitor for application crashes, segmentation faults, or unexpected restarts that may indicate exploitation attempts. Look for signs of memory corruption or abnormal process behavior.

SentinelOne Singularity Platform:
SentinelOne's Singularity platform provides comprehensive protection for OT/ICS environments through:

• Real-time behavioral analysis to detect exploitation attempts
• Network traffic inspection for anomalous PLC communications
• Asset discovery and vulnerability management for industrial devices
• Integration with SIEM/SOAR platforms for centralized alerting

Monitoring Recommendations

1. Network Segmentation Monitoring: Ensure PLCs are properly segmented and monitor for unauthorized access attempts from non-OT network segments
2. Baseline Traffic Analysis: Establish normal communication patterns for Circutor devices and alert on deviations
3. Firmware Version Tracking: Maintain an accurate inventory of PLC firmware versions to identify vulnerable devices
4. Access Logging: Enable and regularly review access logs for the PLC web management interface
5. Periodic Vulnerability Scanning: Include industrial control devices in regular vulnerability assessments

How to Mitigate CVE-2025-11785

Immediate Actions Required

• Identify all Circutor SGE-PLC1000 and SGE-PLC50 devices running firmware version 9.0.2 in your environment
• Implement network segmentation to isolate vulnerable PLCs from untrusted network segments
• Restrict access to PLC management interfaces to authorized personnel and systems only
• Enable logging and monitoring on affected devices to detect potential exploitation attempts
• Review and restrict firewall rules to limit adjacent network access to the PLCs

Patch Information

Consult the INCIBE-CERT advisory for the latest patch information from Circutor: https://www.incibe.es/en/incibe-cert/notices/aviso-sci/multiple-vulnerabilities-circutor-products-0

Organizations should contact Circutor directly for firmware updates that address this vulnerability. Apply patches according to your organization's change management process, prioritizing critical OT systems.

Workarounds

If patching is not immediately possible, implement the following compensating controls:

Network Access Controls:
Restrict network access to the vulnerable PLC devices by implementing strict firewall rules that limit which hosts can communicate with the PLC management interface.

Input Validation at Network Edge:
Deploy a web application firewall (WAF) or reverse proxy in front of the PLC web interface that can validate and sanitize input parameters, rejecting requests with oversized meter parameter values.

VPN/Jump Host Architecture:
Require all administrative access to PLCs go through a hardened jump host or VPN, reducing the attack surface by limiting adjacent network exposure.

# Example firewall rule to restrict PLC access (adjust IP addresses as needed)
# Allow only management workstation to access PLC
iptables -A INPUT -s 192.168.1.100/32 -d <PLC_IP> -p tcp --dport 80 -j ACCEPT
iptables -A INPUT -s 192.168.1.100/32 -d <PLC_IP> -p tcp --dport 443 -j ACCEPT
# Block all other adjacent network access
iptables -A INPUT -d <PLC_IP> -p tcp --dport 80 -j DROP
iptables -A INPUT -d <PLC_IP> -p tcp --dport 443 -j DROP