Modicon M340, M580, Quantum, Premium Controllers Security Notification

This document is a security notification from Schneider Electric detailing a high-severity Denial of Service vulnerability (CVE-2019-6819) in Modicon M340, M580, Quantum, and Premium controllers due to improper handling of specific Modbus frames. It provides remediation steps, including firmware updates for M340 (V3.01) and M580 (V2.80), and recommends network segmentation and firewall blocking of port 502/TCP for end-of-life Quantum and Premium controllers.