CVE-2025-0814 Overview
CVE-2025-0814 is an improper input validation vulnerability [CWE-20] affecting Schneider Electric products that implement the IEC61850-MMS protocol. An unauthenticated attacker can send malicious IEC61850-MMS packets over the network to disrupt network services running on the device. The core breaker functionality remains operational during the attack, but affected network services enter a denial-of-service state. Schneider Electric published a security advisory tracking this issue as SEVD-2025-042-04.
Critical Impact
Remote, unauthenticated attackers can trigger denial-of-service against IEC61850-MMS network services on affected industrial equipment, degrading monitoring and control communications.
Affected Products
- Schneider Electric products implementing IEC61850-MMS communications (see vendor advisory SEVD-2025-042-04)
- Devices exposing IEC61850-MMS network services to untrusted networks
- Industrial breaker devices using the affected protocol stack
Discovery Timeline
- 2025-02-13 - CVE-2025-0814 published to NVD
- 2026-06-17 - Last updated in NVD database
Technical Details for CVE-2025-0814
Vulnerability Analysis
The vulnerability resides in the handling of IEC61850 Manufacturing Message Specification (MMS) packets. IEC61850-MMS is a protocol used in substation automation and industrial control environments to exchange real-time data between intelligent electronic devices (IEDs). The affected component does not correctly validate fields within incoming MMS packets. When malformed input reaches the protocol parser, network services on the device fail, resulting in loss of communications with supervisory systems.
The breaker's core operating logic remains intact, so physical protection functions continue to operate. However, the loss of network services impairs remote monitoring, telemetry, and command channels used by SCADA and engineering workstations. In operational technology environments, the loss of visibility during a control incident can extend recovery time and complicate root-cause analysis.
Root Cause
The root cause is improper input validation [CWE-20] in the IEC61850-MMS packet processing path. Specific packet structures are not sanitized before use, causing the network service handling MMS traffic to terminate or become unresponsive. Full technical details are described in the Schneider Electric Security Notice SEVD-2025-042-04.
Attack Vector
Exploitation requires network reachability to the target device on the IEC61850-MMS TCP port (typically 102). No authentication or user interaction is required. An attacker with access to the OT network segment carrying MMS traffic can craft and send malicious packets to trigger the condition. Because IEC61850-MMS is intended for trusted substation networks, exposure through flat networks or insufficient segmentation increases risk.
No verified public proof-of-concept code is available. The vulnerability mechanism is described in vendor documentation without exploit samples.
Detection Methods for CVE-2025-0814
Indicators of Compromise
- Unexpected loss of IEC61850-MMS service availability on affected devices while physical protection functions continue operating
- Anomalous or malformed MMS packets destined for TCP port 102 on IEDs
- Sudden gaps in SCADA telemetry from affected breakers without corresponding physical events
Detection Strategies
- Deploy OT-aware network intrusion detection to inspect IEC61850-MMS traffic for protocol conformance violations
- Baseline normal MMS communication patterns and alert on deviations in packet size, structure, or source
- Correlate device network-service outages with concurrent traffic from unauthorized sources on the substation LAN
Monitoring Recommendations
- Log connection attempts to TCP port 102 from hosts outside the approved engineering workstation and SCADA subnet
- Monitor device health telemetry and SNMP traps for service restarts on affected equipment
- Forward OT network flow data and IDS alerts into a centralized SIEM for cross-domain correlation with IT events
How to Mitigate CVE-2025-0814
Immediate Actions Required
- Review the Schneider Electric Security Notice SEVD-2025-042-04 and identify all affected devices in the environment
- Restrict network reachability to IEC61850-MMS services so only authorized engineering workstations and SCADA hosts can connect
- Apply vendor-provided firmware updates or remediations as specified in the advisory once available
Patch Information
Refer to Schneider Electric advisory SEVD-2025-042-04 for the current list of fixed firmware versions and mitigation guidance. Follow the vendor's change-management procedure for industrial devices, including staged rollout and validation in a test environment before production deployment.
Workarounds
- Enforce strict network segmentation between IT and OT networks, isolating substation LANs carrying MMS traffic
- Use firewalls and access control lists to permit MMS traffic (TCP 102) only from explicitly authorized sources
- Disable IEC61850-MMS services on devices where the protocol is not required
- Deploy protocol-aware filtering appliances to drop malformed MMS packets before they reach IEDs
# Example firewall rule restricting IEC61850-MMS (TCP/102) to authorized SCADA host
iptables -A INPUT -p tcp --dport 102 -s 10.10.20.5 -j ACCEPT
iptables -A INPUT -p tcp --dport 102 -j DROP
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
