CVE-2025-11778 Overview
CVE-2025-11778 is a critical stack-based buffer overflow vulnerability affecting Circutor SGE-PLC1000 and SGE-PLC50 programmable logic controllers running firmware version 0.9.2. This vulnerability allows an attacker to remotely exploit memory corruption through the read_packet() function of the TACACSPLUS implementation, potentially leading to complete system compromise.
The vulnerability is classified under CWE-122 (Heap-based Buffer Overflow), though the primary attack vector involves stack-based memory corruption. With a CVSS 4.0 score of 10.0 (Critical), this vulnerability represents the maximum severity rating, indicating that successful exploitation requires no user interaction, no privileges, and can be performed remotely over the network with low attack complexity.
Critical Impact
Remote attackers can exploit this stack-based buffer overflow to achieve arbitrary code execution on vulnerable Circutor PLC devices, potentially compromising critical industrial control systems and infrastructure.
Affected Products
- Circutor SGE-PLC1000 Firmware v0.9.2
- Circutor SGE-PLC1000 Hardware
- Circutor SGE-PLC50 Firmware v0.9.2
- Circutor SGE-PLC50 Hardware
Discovery Timeline
- 2025-12-02 - CVE-2025-11778 published to NVD
- 2025-12-03 - Last updated in NVD database
Technical Details for CVE-2025-11778
Vulnerability Analysis
The vulnerability resides in the read_packet() function within the TACACSPLUS (Terminal Access Controller Access-Control System Plus) implementation on Circutor SGE-PLC1000 and SGE-PLC50 devices. TACACS+ is commonly used for authentication, authorization, and accounting (AAA) services in network infrastructure.
The stack-based buffer overflow occurs when the read_packet() function processes incoming TACACS+ packets without proper bounds checking. An attacker can craft malicious TACACS+ packets with oversized data fields that exceed the allocated buffer size on the stack, causing memory corruption.
The CVSS 4.0 vector CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H indicates:
- Attack Vector (AV:N): Network-accessible without requiring local access
- Attack Complexity (AC:L): Low complexity to exploit
- Privileges Required (PR:N): No authentication needed
- User Interaction (UI:N): No user action required
- Impact: High confidentiality, integrity, and availability impact on both the vulnerable system and subsequent systems
The EPSS (Exploit Prediction Scoring System) score of 0.056% places this vulnerability in the 17.62nd percentile, indicating a relatively low probability of exploitation in the wild as of the assessment date.
Root Cause
The root cause of CVE-2025-11778 is improper input validation and insufficient bounds checking in the read_packet() function. When processing TACACS+ protocol packets, the function allocates a fixed-size buffer on the stack to store incoming packet data. The function fails to verify that the incoming data length does not exceed the buffer capacity before copying the data, leading to a classic stack-based buffer overflow condition.
This type of vulnerability in industrial control system (ICS) devices is particularly concerning because:
- PLCs often run with elevated privileges
- Firmware updates may be infrequent in industrial environments
- The devices may be exposed on networks without adequate segmentation
Attack Vector
The attack vector for CVE-2025-11778 is network-based, targeting the TACACS+ service running on vulnerable Circutor PLC devices. An attacker can exploit this vulnerability by sending specially crafted TACACS+ packets to the target device.
The exploitation process involves sending malformed TACACS+ authentication or authorization packets with carefully constructed payloads that overflow the stack buffer in the read_packet() function. By controlling the overflowed data, an attacker can overwrite the return address on the stack and redirect execution flow to attacker-controlled code.
For detailed technical information about this vulnerability, refer to the INCIBE-CERT security advisory.
Detection Methods for CVE-2025-11778
Indicators of Compromise
- Unusual or malformed TACACS+ traffic targeting Circutor PLC devices on the network
- Unexpected crashes or reboots of SGE-PLC1000 or SGE-PLC50 devices
- Anomalous network connections originating from PLC devices to external or unusual destinations
- Memory corruption artifacts or unexpected process behavior on affected devices
- Authentication failures or anomalies in TACACS+ logs
Detection Strategies
Network-based detection should focus on monitoring TACACS+ traffic (typically TCP port 49) for anomalous packet sizes or malformed protocol structures. Security teams should implement:
- Network Traffic Analysis: Deploy network monitoring to identify TACACS+ packets with abnormally large data fields or malformed headers targeting Circutor devices
- IDS/IPS Rules: Configure intrusion detection and prevention systems with signatures for TACACS+ protocol anomalies and buffer overflow attack patterns
- Asset Inventory: Maintain accurate inventory of all Circutor SGE-PLC1000 and SGE-PLC50 devices and their firmware versions
- Behavioral Monitoring: Monitor PLC devices for unexpected behavior, including unusual network activity, process crashes, or memory consumption anomalies
Monitoring Recommendations
Organizations should implement continuous monitoring of their industrial control system networks with specific attention to:
- TACACS+ traffic patterns and volumes to/from PLC devices
- System logs from Circutor devices for authentication anomalies
- Network segmentation effectiveness between IT and OT environments
- Firmware version tracking to ensure vulnerable versions are identified and prioritized for patching
SentinelOne Singularity platform provides comprehensive protection against memory corruption exploits through behavioral AI detection and real-time memory protection capabilities. For ICS/SCADA environments, implementing SentinelOne on engineering workstations and HMI systems provides an additional layer of defense against lateral movement following PLC compromise.
How to Mitigate CVE-2025-11778
Immediate Actions Required
- Identify all Circutor SGE-PLC1000 and SGE-PLC50 devices running firmware version 0.9.2 in your environment
- Implement network segmentation to isolate vulnerable PLC devices from untrusted networks
- Disable TACACS+ services on affected devices if not required for operations
- Apply firewall rules to restrict TACACS+ traffic (TCP port 49) to only authorized management systems
- Monitor for security updates from Circutor and apply patches immediately when available
Patch Information
As of the last NVD update on 2025-12-03, organizations should consult the INCIBE-CERT advisory for the latest patch information from Circutor. Contact Circutor directly for firmware updates addressing CVE-2025-11778.
Given the critical severity (CVSS 10.0) and network attack vector, patching should be prioritized as soon as updates become available. Organizations should follow their change management procedures for ICS environments while expediting the remediation timeline.
Workarounds
If immediate patching is not possible, implement the following compensating controls:
- Network Isolation: Place affected PLC devices on isolated network segments with strict access controls
- Disable TACACS+: If TACACS+ authentication is not operationally required, disable the service entirely on affected devices
- Access Control Lists: Implement strict firewall rules to permit TACACS+ traffic only from known, trusted management IP addresses
- VPN/Jump Hosts: Require all management access to PLC devices through secured VPN connections or hardened jump hosts
- Enhanced Monitoring: Implement heightened monitoring for any anomalous activity targeting the affected devices
Network segmentation is critical for ICS environments. Ensure that PLC devices are not directly accessible from corporate networks or the internet. Follow IEC 62443 guidelines for industrial network architecture and implement defense-in-depth strategies.
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
