CVE-2021-33541: Phoenixcontact ILC1X0 Firmware

High severity, CVSS 7.5. EPSS: 1.5% chance of exploitation in the next 30 days.

Phoenix Contact Classic Line Controllers ILC1x0 and ILC1x1 in all versions/variants are affected by a Denial-of-Service vulnerability. The communication protocols and device access do not feature authentication measures. Remote attackers can use specially crafted IP packets to cause a denial of service on the PLC's network communication module. A successful attack stops all network communication. To restore the network connectivity the device needs to be restarted. The automation task is not affected.

Affected products

Published 2021-06-25. Last modified 2026-06-17.