CVE-2026-14917 in Enterprise Gateway
Summary
by MITRE • 09/16/2026
A SAML authentication bypass vulnerability affects the Kong SAML plugin when the validate_assertion_signature option is explicitly set to false. This option is enabled by default. When disabled, the plugin may extract the SAML identity from an unsigned assertion and authenticate the user without verifying a valid cryptographic signature.
As a result, an unauthenticated remote attacker may be able to submit a crafted SAML response and impersonate arbitrary users, including administrators
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Analysis
by VulDB Data Team • 09/16/2026
The Kong SAML authentication plugin contains a critical security flaw related to the validation of XML Signature assertions within Security Assertion Markup Language responses. This vulnerability specifically manifests when the validate_assertion_signature configuration option is explicitly set to false. Although this setting is disabled by default in standard configurations, its explicit activation creates a significant attack surface for remote attackers seeking to bypass authentication mechanisms. The core technical issue lies in the plugin's failure to perform cryptographic verification of the SAML assertion signature before processing identity claims. In a properly secured implementation, the service provider must verify that the digital signature on the assertion matches the public key of the identity provider, ensuring both integrity and authenticity. By disabling this check, the system accepts any SAML response structure provided by the client without confirming its origin or tamper-evidence.
This architectural weakness allows an unauthenticated remote attacker to craft a malicious SAML response containing arbitrary user attributes. Since the plugin does not verify the signature, it blindly trusts the identity information contained within the assertion body. Consequently, an attacker can inject claims that designate themselves as any valid user in the system, including privileged administrative accounts. This bypass effectively neutralizes the authentication layer provided by the external Identity Provider, allowing direct access to protected resources based solely on forged metadata rather than verified credentials. The impact is severe, as it leads to a complete compromise of account integrity and potential full control over the application environment if an administrator role is impersonated.
From a classification perspective, this vulnerability aligns with CWE-287, which describes Improper Authentication, specifically involving the failure to verify cryptographic signatures during identity assertion processing. It also maps directly to MITRE ATT&CK technique T1651, Cloud Service Session Hacking, where attackers exploit misconfigurations or flaws in cloud-based authentication services to gain unauthorized access. The exploitation vector is remote and requires no prior credentials, making it a high-severity risk for any deployment that explicitly disables signature validation.
To mitigate this vulnerability, organizations must ensure that the validate_assertion_signature option remains enabled at its default value of true. This ensures that all incoming SAML assertions are cryptographically verified against the trusted identity provider's public key before any user session is established or privileges are granted. If there is a specific operational requirement to disable signature validation for testing purposes, this configuration must never be applied in production environments and should be strictly isolated from external-facing endpoints. Additionally, implementing strict logging of authentication failures related to signature mismatches can aid in detecting attempted exploitation activities. Regular security audits of plugin configurations are essential to prevent such misconfigurations from persisting in live systems.