Siemens SIMATIC S7-PLCSIM

As of January 10, 2023, CISA will no longer be updating ICS security advisories for Siemens product vulnerabilities beyond the initial advisory. For the most up-to-date information on vulnerabilities in this advisory, please see Siemens' ProductCERT Security Advisories (CERT Services | Services | Siemens Global).

View CSAF

1. EXECUTIVE SUMMARY

• CVSS v4 8.5
• ATTENTION: Low attack complexity
• Vendor: Siemens
• Equipment: SIMATIC S7-PLCSIM
• Vulnerability: Deserialization of Untrusted Data

2. RISK EVALUATION

Successful exploitation of this vulnerability could allow an attacker to cause a type confusion and execute arbitrary code within the affected application.

3. TECHNICAL DETAILS

3.1 AFFECTED PRODUCTS

Siemens reports that the following products are affected:

• SIMATIC S7-PLCSIM V17: All versions
• SIMOCODE ES V17: All versions
• SIMOCODE ES V18: All versions
• SIMOCODE ES V19: All versions
• SIMOCODE ES V20: All versions
• SIMOTION SCOUT TIA V5.4: All versions
• SIMOTION SCOUT TIA V5.5: All versions
• SIMOTION SCOUT TIA V5.6: All versions prior to V5.6 SP1 HF7
• SIMOTION SCOUT TIA V5.7: All versions
• SINAMICS Startdrive V17: All versions
• SINAMICS Startdrive V18: All versions
• SIMATIC STEP 7 V17: All versions
• SINAMICS Startdrive V19: All versions
• SINAMICS Startdrive V20: All versions
• SIRIUS Safety ES V17 (TIA Portal): All versions
• SIRIUS Safety ES V18 (TIA Portal): All versions
• SIRIUS Safety ES V19 (TIA Portal): All versions
• SIRIUS Safety ES V20 (TIA Portal): All versions
• SIRIUS Soft Starter ES V17 (TIA Portal): All versions
• SIRIUS Soft Starter ES V18 (TIA Portal): All versions
• SIRIUS Soft Starter ES V19 (TIA Portal): All versions
• SIRIUS Soft Starter ES V20 (TIA Portal): All versions
• SIMATIC STEP 7 V18: All versions
• TIA Portal Cloud V17: All versions
• TIA Portal Cloud V18: All versions
• TIA Portal Cloud V19: Versions prior to V5.2.1.1
• TIA Portal Cloud V20: All versions
• SIMATIC STEP 7 V19: All versions prior to V19 Update 4
• SIMATIC STEP 7 V20: All versions
• SIMATIC WinCC V17: All versions
• SIMATIC WinCC V18: All versions
• SIMATIC WinCC V19: All versions prior to V19 Update 4
• SIMATIC WinCC V20: All versions

3.2 VULNERABILITY OVERVIEW

3.2.1 DESERIALIZATION OF UNTRUSTED DATA CWE-502

Affected products do not properly sanitize stored security properties when parsing project files. This could allow an attacker to cause a type confusion and execute arbitrary code within the affected application.

CVE-2025-40759 has been assigned to this vulnerability. A CVSS v3.1 base score of 7.8 has been calculated; the CVSS vector string is (CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H).

A CVSS v4 score has also been calculated for CVE-2025-40759. A base score of 8.5 has been calculated; the CVSS vector string is (CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:P/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N).

3.3 BACKGROUND

• CRITICAL INFRASTRUCTURE SECTORS: Critical Manufacturing
• COUNTRIES/AREAS DEPLOYED: Worldwide
• COMPANY HEADQUARTERS LOCATION: Germany

3.4 RESEARCHER

Siemens reported this vulnerability to CISA.

4. MITIGATIONS

Siemens has identified the following specific workarounds and mitigations users can apply to reduce risk:

• All affected products: Only open projects from trusted sources.
• SIMATIC S7-PLCSIM V17: Currently no fix is planned
• SIMATIC STEP 7 V17, SIMATIC STEP 7 V18, SIMATIC STEP 7 V20, SIMATIC WinCC V17, SIMATIC WinCC V18, SIMATIC WinCC V20, SIMOCODE ES V17, SIMOCODE ES V18, SIMOCODE ES V19, SIMOCODE ES V20, SIMOTION SCOUT TIA V5.4, SIMOTION SCOUT TIA V5.5, SIMOTION SCOUT TIA V5.7, SINAMICS Startdrive V17, SINAMICS Startdrive V18, SINAMICS Startdrive V19, SINAMICS Startdrive V20, SIRIUS Safety ES V17 (TIA Portal), SIRIUS Safety ES V18 (TIA Portal), SIRIUS Safety ES V19 (TIA Portal), SIRIUS Safety ES V20 (TIA Portal), SIRIUS Soft Starter ES V17 (TIA Portal), SIRIUS Soft Starter ES V18 (TIA Portal), SIRIUS Soft Starter ES V19 (TIA Portal), SIRIUS Soft Starter ES V20 (TIA Portal), TIA Portal Cloud V17, TIA Portal Cloud V18, TIA Portal Cloud V20: Currently no fix is available
• SIMATIC STEP 7 V19, SIMATIC WinCC V19: Update to V19 Update 4 or later version
• SIMOTION SCOUT TIA V5.6: Update to V5.6 SP1 HF7 or later version
• TIA Portal Cloud V19: TIA Portal Cloud V5.2.1.1 or later version updated TIA Portal to V19 Update 4 or later version

As a general security measure, Siemens recommends protecting network access to devices with appropriate mechanisms. To operate the devices in a protected IT environment, Siemens recommends configuring the environment according to Siemens' operational guidelines for industrial security and following recommendations in the product manuals.

Additional information on industrial security by Siemens can be found on the Siemens industrial security webpage

For more information see the associated Siemens security advisory SSA-493396 in HTML and CSAF.

CISA recommends users take defensive measures to minimize the risk of exploitation of this vulnerability, such as:

• Minimize network exposure for all control system devices and/or systems, ensuring they are not accessible from the internet.
• Locate control system networks and remote devices behind firewalls and isolating them from business networks.
• When remote access is required, use more secure methods, such as Virtual Private Networks (VPNs). Recognize VPNs may have vulnerabilities, should be updated to the most recent version available, and are only as secure as the 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.

CISA also recommends users take the following measures to protect themselves from social engineering attacks:

• Do not click web links or open attachments in unsolicited email messages.
• Refer to Recognizing and Avoiding Email Scams for more information on avoiding email scams.
• Refer to Avoiding Social Engineering and Phishing Attacks for more information on social engineering attacks.

No known public exploitation specifically targeting this vulnerability has been reported to CISA at this time. This vulnerability is not exploitable remotely.

5. UPDATE HISTORY

• August 14, 2025: Initial Republication of Siemens ProductCERT SSA-493396

• Siemens