CVE-2018-7854 Schneider Electric CVE debrief

Who should care

Schneider Electric Modicon M580 and M340 operators, industrial control system administrators, OT network defenders, system integrators, and plant engineers who manage Modbus-connected controllers or engineering workstations.

Technical summary

The source advisory says the controller can throw an uncaught exception when invalid debug parameters are sent over Modbus, resulting in denial of service. CISA’s CSAF content maps the issue to Modicon M580 firmware versions prior to v2.90 and Modicon M340 firmware versions prior to v3.10. Vendor remediations later specify fixed firmware releases of M580 SV4.20 and M340 v3.60, plus workstation/project updates in EcoStruxure Control Expert and project rebuild/transfer steps. The mitigation guidance also recommends application passwords, network segmentation, blocking unauthorized access to TCP/502, access control lists, secure communications, and IPsec or external firewall options where applicable.

Defensive priority

High. The issue affects controller availability and is reachable through Modbus, so it should be prioritized wherever controllers are reachable from shared OT networks, remote maintenance paths, or inadequately segmented engineering environments.

Recommended defensive actions

• Update Modicon M580 controllers to firmware SV4.20 or later and update EcoStruxure Control Expert to v16.0 as directed by the vendor.
• Update Modicon M340 controllers to firmware v3.60 or later and update EcoStruxure Control Expert to v16.0 or later as directed by the vendor.
• Rebuild and transfer affected projects after updating firmware, and ensure the project firmware version matches the target controller.
• Set an application password in project properties.
• Restrict and segment OT networks so unauthorized access to TCP/502 is blocked.
• Apply controller access control list recommendations from the relevant Schneider Electric manuals.
• Use secure communication guidance from Schneider Electric, including IPsec where applicable, and consider external firewall/VPN protections for M580/M340 architectures.
• For M580 deployments, enable CPU memory protection where supported; follow vendor guidance for Hot Standby exceptions.

Evidence notes

Primary evidence comes from the CISA CSAF source item for ICSA-25-114-01 and its linked Schneider Electric notices. The source description states: "An uncaught exception vulnerability exists which could cause a denial of service when sending invalid debug parameters to the controller over Modbus." The CSAF product tree and affected products identify Modicon M580 firmware versions prior to v2.90 and Modicon M340 firmware versions prior to v3.10. The remediations list vendor-fixed firmware versions of M580 SV4.20 and M340 v3.60, plus mitigation steps including application passwords, segmentation, TCP/502 filtering, ACLs, secure communications, and IPsec/external firewall options. The revision history shows the advisory original release on 2019-05-14 and later content updates through 2020-12-08; the source mirror metadata is modified later, but the CVE publication date used here is the supplied 2019-05-14 value.

Official resources