CVE-2018-16561: A vulnerability has been identified in SIMATIC S7-300 CPUs (All versions < V3.X.16). The affected CPUs improperly validate S7 communication packets wh...

Description

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.

Metrics

CVSS 3.1

7.5/10

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

EPSS Probability

1.36%

68.2th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-20

Affected Software

Vendor	Product	Versions
Siemens	Simatic S7-300 Firmware	All versions
Siemens	Simatic S7-300f Firmware	All versions
Siemens	Simatic S7-300fs Firmware	All versions
Siemens	Simatic S7-300t Firmware	All versions

References

https://cert-portal.siemens.com/productcert/pdf/ssa-306710.pdfVendor Advisory
https://cert-portal.siemens.com/productcert/pdf/ssa-306710.pdfVendor Advisory

Timeline

Published: Apr 17, 2019
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2018-16561?

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.

How severe is CVE-2018-16561?

CVE-2018-16561 has a CVSS score of 7.5/10 (HIGH severity). The EPSS model estimates a 1.36% probability of exploitation in the next 30 days.

How do I fix CVE-2018-16561?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.