rslinx classic

RSLinx Classic is Rockwell Automation's legacy OPC and DDE server software used to connect Allen-Bradley programmable logic controllers (PLCs) to Windows-based human-machine interfaces (HMIs) and other applications. Discussions on WindowsForum.com highlight a CISA advisory warning that RSLinx Classic versions 4.50.00 and earlier are affected by CVE-2020-13573, a remotely exploitable denial-of-service vulnerability that can render the application unresponsive until manual intervention. This issue is particularly relevant for industrial Windows systems still running outdated middleware in operational technology environments. The forum content emphasizes that while the CVE is not new, its ongoing risk underscores the importance of patching legacy software to maintain business continuity in plants, utilities, and process control settings.