Siemens Mendix Runtime

Summary

A critical documentation gap in Siemens Mendix Runtime (CVE-2026-7891, CVSS 9.1) leaves developers without adequate guidance on configuring access rules for the System.User entity securely. The vulnerability allows overly permissive access rules to be applied, potentially exposing sensitive user data or enabling privilege escalation in deployed applications. The misconfiguration commonly affects anonymous user roles gaining unintended access to all stored records.

Full text

ICS Advisory Siemens Mendix Runtime Release DateJuly 28, 2026 Alert CodeICSA-26-209-02 Related topics: Industrial Control System Vulnerabilities , Industrial Control Systems View CSAF Summary Mendix documentation for access rules does not adequately describe the special behavior of the System.User entity, leaving developers without sufficient guidance to configure access rules securely. This documentation gap may lead application developers to unknowingly apply overly permissive access rules to System.User, resulting in unintended exposure of sensitive user data or privilege escalation within deployed Mendix applications. A common misconfiguration identified is with the anonymous user role with a System.User entity to gain access to all stored records, even though no access rights are explicitly configured on that role. Siemens recommends Mendix developers to review their access rules based on updated documentation. The following versions of Siemens Mendix Runtime are affected: Mendix Runtime vers:all/* (CVE-2026-7891) CVSS Vendor Equipment Vulnerabilities v3 9.1 Siemens Siemens Mendix Runtime Insecure Inherited Permissions Background Critical Infrastructure Sectors: Critical Manufacturing Countries/Areas Deployed: Worldwide Company Headquarters Location: Germany Vulnerabilities Expand All + CVE-2026-7891 Mendix documentation for access rules does not adequately describe the special behavior of the System.User entity, leaving developers without sufficient guidance to configure access rules securely. This documentation gap may lead application developers to unknowingly apply overly permissive access rules to System.User, resulting in unintended exposure of sensitive user data or privilege escalation within deployed Mendix applications. View CVE Details Affected Products Siemens Mendix Runtime Vendor:Siemens Product Version:Mendix Runtime Product Status:known_affected Remediations MitigationAny security model relying solely on XPath constraints on a System.User specialization to restrict access should be revised to enforce restrictions at the App Security role-management configuration level instead. Vendor fixReview mendix access rules knowing that System.User has built-in platform-enforced access rules that cannot be overridden or restricted by access rules defined on a specialization. Check updated documentation for further details Relevant CWE: CWE-277 Insecure Inherited Permissions Metrics CVSS Version Base Score Base Severity Vector String 3.1 9.1 CRITICAL CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N 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-814963 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-814963 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-26-209-03 Siemens SIMATIC S7-PLCSIM Advanced 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-2026-7891

Entities