Siemens SIMATIC S7-PLCSIM Advanced

Summary

A vulnerability in Siemens SIMATIC S7-PLCSIM Advanced (CVE-2026-54429) could allow an unauthenticated attacker on the local network to cause a denial-of-service condition by exhausting memory resources through high-volume multicast traffic. While no fix is currently available, Siemens recommends specific mitigations, including disabling S7-PLCSIM Virtual Switch binding or restricting multicast traffic.

Full text

ICS Advisory Siemens SIMATIC S7-PLCSIM Advanced Release DateJuly 28, 2026 Alert CodeICSA-26-209-03 Related topics: Industrial Control System Vulnerabilities , Industrial Control Systems View CSAF Summary SIMATIC S7-PLCSIM Advanced contains a vulnerability that could allow an attacker to cause a denial of service condition. Siemens is preparing fix versions and recommends specific countermeasures for products where fixes are not, or not yet available. The following versions of Siemens SIMATIC S7-PLCSIM Advanced are affected: SIMATIC S7-PLCSIM Advanced vers:all/* (CVE-2026-54429) CVSS Vendor Equipment Vulnerabilities v3 7.4 Siemens Siemens SIMATIC S7-PLCSIM Advanced Allocation of Resources Without Limits or Throttling Background Critical Infrastructure Sectors: Critical Manufacturing Countries/Areas Deployed: Worldwide Company Headquarters Location: Germany Vulnerabilities Expand All + CVE-2026-54429 Affected devices do not properly handle high-volume multicast network traffic, which can exhaust available memory resources in the affected application. This could allow an unauthenticated attacker on the local network segment to cause a denial-of-service condition of the affected application. The affected application becomes inaccessible and requires a manual restart; no project data is lost. Successful exploitation requires a specific project configuration to be already active on the targeted instance. View CVE Details Affected Products Siemens SIMATIC S7-PLCSIM Advanced Vendor:Siemens Product Version:SIMATIC S7-PLCSIM Advanced Product Status:known_affected Remediations MitigationDisable the S7-PLCSIM Virtual Switch binding on the network adapter used by the affected instance. This prevents the adapter from entering an external communication mode and removes the attack vector entirely. (see SIMATIC S7-PLCSIM Advanced Function Manual V8.0, 11/2025 Section 5.3 and Section 6.1.2.3; and SIMATIC S7-PLCSIM Advanced Function Manual API V8.0, 11/2025 Section 7.2) MitigationRestrict multicast traffic on the network segment hosting the SIMATIC S7-PLCSIM Advanced host. MitigationUse 'Softbus' / 'PLCSIM' network mode. This mode does not accept any packets from the network. This mode is a default network mode. (see SIMATIC S7-PLCSIM Advanced Function Manual V8.0, 11/2025 Section 5.0 and Section 5.1; and SIMATIC S7-PLCSIM Advanced Function Manual API V8.0, 11/2025 Section 7.2) None availableCurrently no fix is available Relevant CWE: CWE-770 Allocation of Resources Without Limits or Throttling Metrics CVSS Version Base Score Base Severity Vector String 3.1 7.4 HIGH CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H Acknowledgments Siemens ProductCERT reported this vulnerability to CISA. General Recommendations As a general security measure, Siemens strongly recommends to protect network access to devices with appropriate mechanisms. In order to operate the devices in a protected IT environment, Siemens recommends to configure the environment according to Siemens' operational guidelines for Industrial Security (Download: https://www.siemens.com/cert/operational-guidelines-industrial-security), and to follow the recommendations in the product manuals. Additional information on Industrial Security by Siemens can be found at: https://www.siemens.com/industrialsecurity Additional Resources For further inquiries on security vulnerabilities in Siemens products and solutions, please contact the Siemens ProductCERT: https://www.siemens.com/cert/advisories Terms of Use The use of Siemens Security Advisories is subject to the terms and conditions listed on: https://www.siemens.com/productcert/terms-of-use. Legal Notice and Terms of Use This product is provided subject to this Notification (https://www.cisa.gov/notification) and this Privacy & Use policy (https://www.cisa.gov/privacy-policy). Recommended Practices CISA recommends users take defensive measures to minimize the exploitation risk of these vulnerabilities. Minimize network exposure for all control system devices and/or systems, and ensure they are not accessible from the internet. Locate control system networks and remote devices behind firewalls and isolate them from business networks. When remote access is required, use more secure methods, such as Virtual Private Networks (VPNs), recognizing VPNs may have vulnerabilities and should be updated to the most recent version available. Also recognize VPN is only as secure as its connected devices. CISA reminds organizations to perform proper impact analysis and risk assessment prior to deploying defensive measures. CISA also provides a section for control systems security recommended practices on the ICS webpage on cisa.gov. Several CISA products detailing cyber defense best practices are available for reading and download, including Improving Industrial Control Systems Cybersecurity with Defense-in-Depth Strategies. CISA encourages organizations to implement recommended cybersecurity strategies for proactive defense of ICS assets. Additional mitigation guidance and recommended practices are publicly available on the ICS webpage at cisa.gov in the technical information paper, ICS-TIP-12-146-01B--Targeted Cyber Intrusion Detection and Mitigation Strategies. Organizations observing suspected malicious activity should follow established internal procedures and report findings to CISA for tracking and correlation against other incidents. Advisory Conversion Disclaimer This ICSA is a verbatim republication of Siemens ProductCERT SSA-828211 from a direct conversion of the vendor's Common Security Advisory Framework (CSAF) advisory. This is republished to CISA's website as a means of increasing visibility and is provided "as-is" for informational purposes only. CISA is not responsible for the editorial or technical accuracy of republished advisories and provides no warranties of any kind regarding any information contained within this advisory. Further, CISA does not endorse any commercial product or service. Please contact Siemens ProductCERT directly for any questions regarding this advisory. Revision History Initial Release Date: 2026-07-14 Date Revision Summary 2026-07-14 1 Publication Date 2026-07-28 2 Initial CISA Republication of Siemens ProductCERT SSA-828211 advisory Legal Notice and Terms of Use This product is provided subject to this Notification and this Privacy & Use policy. Vendor Siemens Tags Sector: Critical Manufacturing Sector Topics: Industrial Control System Vulnerabilities, Industrial Control Systems Please share your thoughts We recently updated our anonymous product survey; we welcome your feedback. Related Advisories Jul 28, 2026 ICS Advisory | ICSA-26-209-02 Siemens Mendix Runtime Jul 28, 2026 ICS Advisory | ICSA-26-209-04 Siemens SIMATIC S7-1500 CPU 1518(F)-4 PN/DP MFP Jul 28, 2026 ICS Advisory | ICSA-26-209-07 ABB KNX Update Tool Jul 28, 2026 ICS Advisory | ICSA-26-209-01 Siemens Desigo CC

Indicators of Compromise

• cve — CVE-2026-54429

Entities