CVE-2025-11786 Overview
CVE-2025-11786 is a stack-based buffer overflow vulnerability [CWE-121] affecting Circutor SGE-PLC1000 and SGE-PLC50 firmware version 9.0.2. The flaw resides in the SetUserPassword() function, which embeds the newPassword parameter directly into a shell command string via sprintf() without sanitization or length validation. The resulting string is then executed using system(), allowing an authenticated attacker on an adjacent network to corrupt the stack and inject arbitrary shell commands. Commands execute with the same privileges as the vulnerable application running on the programmable logic controller.
Critical Impact
Successful exploitation enables arbitrary command execution on industrial control devices used in energy management, exposing operational technology environments to disruption and lateral movement.
Affected Products
- Circutor SGE-PLC1000 firmware 9.0.2
- Circutor SGE-PLC50 firmware 9.0.2
- Circutor SGE-PLC1000 and SGE-PLC50 hardware appliances running the affected firmware
Discovery Timeline
- 2025-12-02 - CVE-2025-11786 published to NVD
- 2025-12-03 - Last updated in NVD database
Technical Details for CVE-2025-11786
Vulnerability Analysis
The vulnerability exists in the password management logic of the Circutor SGE-PLC1000 and SGE-PLC50 firmware. The SetUserPassword() function constructs a shell command by concatenating the attacker-controlled newPassword parameter into a fixed-size stack buffer using sprintf(). Because sprintf() performs no bounds checking, supplying a newPassword value longer than the destination buffer corrupts adjacent stack memory, including saved return addresses and frame pointers.
The same code path then passes the constructed string to system(), which spawns a shell to execute the command. This dual weakness means an attacker can either trigger memory corruption for control-flow hijacking or inject shell metacharacters such as ;, &&, or | to execute arbitrary operating system commands. The injected commands inherit the privileges of the application process on the PLC.
Root Cause
The root cause is the unsafe combination of sprintf() for string formatting and system() for command execution against an untrusted input. Neither input length validation nor metacharacter escaping is applied to the newPassword parameter before it reaches either function call.
Attack Vector
Exploitation requires adjacent network access and low-privilege authenticated credentials on the device. An attacker submits a crafted password value through the password change interface. The supplied string either overflows the stack buffer or breaks out of the intended command using shell separators, resulting in arbitrary command execution on the PLC.
No verified public proof-of-concept code is available. Technical details are documented in the INCIBE Security Notice.
Detection Methods for CVE-2025-11786
Indicators of Compromise
- Unexpected shell processes spawned by the PLC web management or password-change service.
- Outbound network connections originating from the SGE-PLC1000 or SGE-PLC50 to unfamiliar hosts.
- Modified or newly created files in firmware-writable directories following password change requests.
- Authentication logs showing repeated password change attempts from a single adjacent host.
Detection Strategies
- Inspect HTTP requests to the password change endpoint for shell metacharacters such as ;, |, &, backticks, or $() inside the newPassword field.
- Flag any newPassword parameter that exceeds the documented maximum password length as a potential overflow attempt.
- Correlate password change activity with subsequent process or configuration changes on the device.
Monitoring Recommendations
- Forward PLC management interface logs to a centralized SIEM for analysis against command-injection patterns.
- Use network intrusion detection on the OT segment to alert on anomalous traffic to and from Circutor devices.
- Monitor for firmware integrity drift and unexpected configuration changes on SGE-PLC1000 and SGE-PLC50 devices.
How to Mitigate CVE-2025-11786
Immediate Actions Required
- Restrict network access to the SGE-PLC1000 and SGE-PLC50 management interfaces to a dedicated, isolated OT management VLAN.
- Rotate device credentials and enforce strong, unique passwords for all PLC user accounts.
- Audit existing user accounts on affected devices and remove any unused or default accounts.
- Review the INCIBE Security Notice for vendor coordination details.
Patch Information
No vendor patch URL is listed in the CVE record at the time of publication. Operators should contact Circutor directly for remediation guidance and monitor the INCIBE advisory for firmware updates superseding version 9.0.2.
Workarounds
- Place affected PLCs behind a firewall that blocks all traffic except from authorized engineering workstations.
- Disable remote password change functionality where operationally feasible.
- Apply network segmentation between IT and OT networks to prevent adjacent-network access from compromised endpoints.
- Require VPN or jump-host access for any administrative session targeting the PLC.
# Example firewall restriction limiting access to PLC management interface
iptables -A FORWARD -s 10.10.20.0/24 -d <plc_ip> -p tcp --dport 443 -j ACCEPT
iptables -A FORWARD -d <plc_ip> -p tcp --dport 443 -j DROP
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
