Summary
Mendix SAML module contains an authentication bypass vulnerability that could allow an unauthenticated remote attacker to gain unauthorized access by replaying a valid SAML assertion in IdP-initiated authentication flows. Siemens has released new versions for the affected products and recommends to update to the latest versions.
The following versions of Siemens Mendix SAML Module are affected:
- Mendix SAML (Mendix 10 compatible) vers:intdot/<4.2.4 (CVE-2026-89209)
- Mendix SAML (Mendix 11 compatible) vers:intdot/<4.2.4 (CVE-2026-89209)
- Mendix SAML (Mendix 9 compatible) vers:intdot/<3.6.29 (CVE-2026-89209)
CVSS
Vendor
Equipment
v3 6.8
Siemens
Mendix SAML (Mendix 10 compatible)
1 Vulnerability
Authentication Bypass by Capture-replay
Background
- Critical Infrastructure Sectors: Critical Manufacturing, Information Technology
- Countries/Areas Deployed: Worldwide
- Company Headquarters Location: Germany
Vulnerabilities
CVE-2026-89209
Affected versions of the module do not properly protect against SAML assertion replay in IdP-initiated authentication flows. This could allow unauthenticated remote attackers to gain unauthorized access to the application by replaying a valid SAML response.
Read More
3 Affected Products
Mendix SAML (Mendix 10 compatible) < V4.2.4
Product Status: known_affected
Remediations
Mitigation
Disable IdP-initiated SSO
Vendor fix
Update to V4.2.4 or later version
Mendix SAML (Mendix 11 compatible) < V4.2.4
Product Status: known_affected
Remediations
Mitigation
Disable IdP-initiated SSO
Vendor fix
Update to V4.2.4 or later version
Mendix SAML (Mendix 9 compatible) < V3.6.29
Product Status: known_affected
Remediations
Mitigation
Disable IdP-initiated SSO
Vendor fix
Update to V3.6.29 or later version
Additional Metrics
Relevant CWE: CWE-294 Authentication Bypass by Capture-replay
CVSS Version
Base Score
Base Severity
Vector String
3.1
6.8
MEDIUM
CVSS:3.1/AV:N/AC:H/PR:N/UI:R/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.
Recommended Practices
CISA recommends users take defensive measures to minimize the risk of exploitation of these vulnerabilities.
- 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), recognizing VPNs may have vulnerabilities and should be updated to the most current version available. Also recognize VPN is 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/ics. 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/ics 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-137528 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
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