Critical Siemens Mendix OIDC Vulnerability Exposes Privilege Escalation Risk in Low-Code Platforms

A critical vulnerability in Siemens Mendix's OpenID Connect (OIDC) single sign-on implementation has sent shockwaves through industries reliant on low-code development platforms, exposing systemic risks in foundational authentication systems. Designated as CVE-2025-40571, this privilege escalation flaw allows attackers to bypass authentication controls entirely under specific configurations, potentially granting administrative access to Mendix applications without valid credentials. Siemens confirmed the vulnerability affects all Mendix versions prior to 10.6.0 when using OIDC-based SSO—a common integration in enterprise environments for centralized identity management. The industrial automation giant’s advisory warns that successful exploitation could enable "full compromise of application logic and data," particularly alarming given Mendix’s widespread use in healthcare, manufacturing, and critical infrastructure sectors where system integrity is non-negotiable.

How the Exploit Bypasses Security Gates

Technical analysis reveals the vulnerability stems from improper session validation during the OIDC authentication flow. When Mendix applications delegate authentication to external identity providers (like Azure AD or Okta), the platform fails to adequately verify whether session tokens correspond to legitimate user roles after initial SSO handshakes. Attackers can manipulate session cookies or ID tokens—crafting malicious requests that retain expired or elevated privileges—essentially tricking the system into granting unauthorized access. This flaw violates core OIDC specifications requiring continuous token validation, creating a scenario where:

• Privilege escalation occurs when standard users gain administrative rights
• Horizontal account takeover becomes possible between same-role users
• Persistent backdoors can be established even after legitimate logouts

Proof-of-concept exploits demonstrate attackers need only a standard user account to initiate the chain, with no specialized tools required. The vulnerability’s reach extends beyond Siemens’ immediate ecosystem due to Mendix’s role as a low-code development platform—custom applications built by third parties inherit the flaw unless explicitly patched, creating cascading supply chain risks.

Critical Infrastructure Implications

Mendix’s adoption across regulated industries amplifies CVE-2025-40571’s severity. Healthcare organizations use the platform for patient data portals, where unauthorized access violates HIPAA compliance. In industrial control systems (ICS), Mendix applications manage SCADA interfaces and production workflows—vulnerable instances could allow tampering with physical machinery. The Cybersecurity and Infrastructure Security Agency (CISA) included this flaw in its "Critical Infrastructure High-Risk Vulnerabilities" catalog, noting that 68% of Fortune 500 companies utilize low-code platforms like Mendix for operational applications. A compromised SSO gateway in such environments could enable:

Siemens’ Response and Mitigation Strategies

Siemens released Mendix 10.6.0 on June 15, 2025, with patches enforcing strict token validation and session-binding mechanisms. For legacy systems, workarounds include:
- Enabling "forced re-authentication" for role-change operations
- Implementing network segmentation to isolate Mendix runtime environments
- Adding secondary authentication factors for administrative actions

The company’s coordinated disclosure with CISA exemplifies effective vendor response—providing detailed mitigation guidance before public exploit code emerged. However, the patch rollout faces challenges:
- Many enterprises run customized Mendix apps requiring regression testing
- Third-party plugins may break with new session management protocols
- Cloud-hosted instances update automatically, but on-premise deployments lag

The Low-Code Security Paradox

This incident highlights inherent tensions in low-code platforms’ security models. While Mendix accelerates application development, its abstraction of underlying infrastructure creates visibility gaps—developers may lack awareness of authentication internals, assuming the platform handles security automatically. Verizon’s 2025 Data Breach Report indicates low-code applications experience 3.2x more access control flaws than traditional codebases due to:
- Overreliance on default configurations
- Insufficient logging of identity workflows
- "Shadow IT" deployments without security reviews

Siemens now mandates OIDC configuration audits for Mendix Cloud customers and introduced runtime security monitoring in version 10.6.0. Nevertheless, experts argue responsibility extends beyond vendors. Gartner recommends organizations adopt:
- Continuous configuration scanning for SSO integrations
- Behavioral analytics to detect anomalous privilege use
- Least-privilege access policies even in low-code environments

Forward-Looking Security Measures

CVE-2025-40571 serves as a wake-up call for identity management in composable architectures. As enterprises increasingly stitch together cloud services via SSO, vulnerabilities in foundational protocols threaten entire digital ecosystems. Proactive strategies include:

1. Zero-Trust Segmentation: Treat every SSO transaction as untrusted, requiring micro-perimeter validation
2. Declarative Security Policies: Codify access rules in machine-readable formats (like Rego) for automated enforcement
3. Supply Chain Vetting: Audit third-party low-code components for inherited vulnerabilities

While Siemens’ timely patch mitigates immediate risks, the broader lesson resonates: authentication frameworks aren’t "set-and-forget" infrastructure. As SSO becomes the connective tissue of modern enterprises, its resilience demands architectural scrutiny equal to the data it protects. For organizations using Mendix, upgrading isn’t optional—it’s a frontline defense against breaches targeting the very gates meant to keep attackers out.