Mendix SAML module vulnerability, which Siemens self-reported, could allow an unauthenticated remote attacker gain unauthorized access by replaying a valid SAML assertion in IdP-initiated authentication flows.
The Siemens Mendix SAML Module is an official application component that enables Single Sign-On (SSO) for Mendix low-code applications using the SAML 2.0 protocol.
The following versions of Siemens Mendix SAML Module suffer from the issue:
- Mendix SAML (Mendix 10 compatible) versions under 4.2.4
- Mendix SAML (Mendix 11 compatible) versions under 4.2.4
- Mendix SAML (Mendix 9 compatible) versions under 3.6.29
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.
CVE-2026-89209 is the case number for the vulnerability which has a CVSS base score of 6.8.
Industrial Sectors
The product sees use in the critical manufacturing and information technology sectors, and on a global basis.
In terms of mitigations:
- For Mendix SAML (Mendix 10 compatible) under version V4.2.4, update to V4.2.4 or later
- For Mendix SAML (Mendix 11 compatible) under version V4.2.4 update to V4.2.4 or later
- For Mendix SAML (Mendix 9 compatible) under version V3.6.29 update to V3.6.29 or later
As a general security measure, Siemens 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.
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