Siemens Mendix SAML
Siemens Mendix SAML module fails signature validation, allowing unauthenticated account hijacking in specific SSO configurations (CVE-2026-80465).
CISA republished Siemens advisory SSA-887643 for CVE-2026-80465 (CVSS 8.7) in the Mendix SAML module, affecting Mendix 10/11-compatible versions before 4.2.3 and Mendix 9.24-compatible versions before 3.6.27. The module improperly validates SAML response signatures (CWE-347), letting unauthenticated remote attackers hijack an account in specific SSO configurations. Mendix has released fixed versions and recommends updating.
- CVE-2026-80465 (CVSS 8.7) stems from improper SAML response signature verification
- Unauthenticated remote attackers can hijack sessions in specific SSO configurations
- Fixes in Mendix SAML 4.2.3 (Mendix 10/11) and 3.6.27 (Mendix 9.24)
Vulnerabilities mentionedAll →
| CVE | Vulnerability | CVSS | EPSS | Flags | Affected | Exposure | Published |
|---|---|---|---|---|---|---|---|
| CVE-2026-80465 | Improper SAML Signature Validation in Mendix SAML Module Enables Account Hijacking CVE-2026-80465 is a cryptographic signature verification flaw (CWE-347) in the Mendix SAML single sign-on module, which fails to properly validate the signature on SAML responses it receives. An unauthenticated remote attacker can trigger it by submitting a crafted SAML response during the SSO login flow, and exploitation is limited to specific SAML SSO configurations (reflected in the High attack complexity and 'Previous attack requirements' in the 8.8 High CVSS 4.0 score). A successful attack allows the attacker to hijack a user account or session, with high confidentiality and integrity impact. Organizations running Mendix applications built on Mendix 9.24, 10, or 11 that use affected versions of the SAML module with SAML-based SSO are affected. There is currently no known public proof-of-concept, no CISA KEV listing, and a low 0.2% EPSS probability, indicating no observed or publicly demonstrated exploitation. Do: Upgrade the Mendix SAML module to V4.2.3 or later for Mendix 10- and 11-compatible apps, and to V3.6.27 or later for Mendix 9.24-compatible apps. Inventory which applications use the SAML module and review their SSO configuration, since only specific SAML SSO setups are exploitable. Although no public PoC or in-the-wild exploitation is known, patch promptly given the high CVSS 4.0 rating and the typical severity of SAML signature bypass flaws. | 8.8 | <1% |
| largetens of thousands of Mendix app deployments with the SAML SSO module active (estimated) |
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Summary
Mendix SAML module contains a vulnerability that could allow unauthenticated remote attackers to hijack an account in specific SSO configurations. Mendix has provided fix releases for the Mendix SAML module and recommends to update to the latest version.
The following versions of Siemens Mendix SAML are affected:
- Mendix SAML (Mendix 10 compatible) vers:intdot/<4.2.3 (CVE-2026-80465)
- Mendix SAML (Mendix 11 compatible) vers:intdot/<4.2.3 (CVE-2026-80465)
- Mendix SAML (Mendix 9.24 compatible) vers:intdot/<3.6.27 (CVE-2026-80465)
| CVSS | Vendor | Equipment | Vulnerabilities |
|---|---|---|---|
| v3 8.7 | Siemens | Siemens Mendix SAML | Improper Verification of Cryptographic Signature |
Background
- Critical Infrastructure Sectors: Critical Manufacturing, Information Technology
- Countries/Areas Deployed: Worldwide
- Company Headquarters Location: Germany
Vulnerabilities
CVE-2026-80465
Affected versions of the module do not properly validate the SAML response signature. This could allow unauthenticated remote attackers to hijack an account (session) in specific SSO configurations.
Affected Products
Siemens Mendix SAML
Vendor:
Siemens
Product Version:
Mendix SAML (Mendix 10 compatible) < V4.2.3, Mendix SAML (Mendix 11 compatible) < V4.2.3, Mendix SAML (Mendix 9.24 compatible) < V3.6.27
Product Status:
known_affected
Relevant CWE: CWE-347 Improper Verification of Cryptographic Signature
Metrics
| CVSS Version | Base Score | Base Severity | Vector String |
|---|---|---|---|
| 3.1 | 8.7 | HIGH | CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:N |
Acknowledgments
- Siemens ProductCERT reported this vulnerability to CISA.
General Recommendations
As a general security measure, Siemens strongly recommends protecting network access to devices with appropriate mechanisms. In order to operate the devices in a protected IT environment, Siemens recommends configuring the environment according to Siemens' operational guidelines for Industrial Security, and following 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
For more information see the associated Siemens security advisory SSA-887643 in HTML and CSAF.
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-887643 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: 2026-09-03
| Date | Revision | Summary |
|---|---|---|
| 2026-09-03 | 1 | Publication Date |
| 2026-09-15 | 2 | Initial CISA Republication of Siemens ProductCERT SSA-887643 advisory |
Legal Notice and Terms of Use
Text extracted automatically; images, tables and formatting may be missing. Original: https://www.cisa.gov/news-events/ics-advisories/icsa-26-258-06