CVE-2018-16561: Siemens SIMATIC s7-300 Firmware

High severity, CVSS 7.5. EPSS: 1.4% chance of exploitation in the next 30 days.

A vulnerability has been identified in SIMATIC S7-300 CPUs (All versions < V3.X.16). The affected CPUs improperly validate S7 communication packets which could cause a Denial-of-Service condition of the CPU. The CPU will remain in DEFECT mode until manual restart. Successful exploitation requires an attacker to be able to send a specially crafted S7 communication packet to a communication interface of the CPU. This includes Ethernet, PROFIBUS, and Multi Point Interfaces (MPI). No user interaction or privileges are required to exploit the security vulnerability. The vulnerability could allow causing a Denial-of-Service condition of the core functionality of the CPU, compromising the availability of the system. At the time of advisory publication no public exploitation of this security vulnerability was known. Siemens confirms the security vulnerability and provides mitigations to resolve the security issue.

Affected products

• Siemens SIMATIC s7-300 Firmware: affected versions not specified
• Siemens SIMATIC s7-300f Firmware: affected versions not specified
• Siemens SIMATIC s7-300fs Firmware: affected versions not specified
• Siemens SIMATIC s7-300t Firmware: affected versions not specified

Published 2019-04-17. Last modified 2026-06-17.