CVE-2026-56679 in 9router
Summary
by MITRE • 07/16/2026
9Router is an AI router & token saver. Prior to 0.5.4, the PATCH /api/settings endpoint writes the entire request body to persistent settings without a field whitelist, allowing an authenticated user to set security-critical fields such as requireLogin and disable authentication for the whole application, exposing protected routes such as /api/keys and /api/providers to unauthenticated access. This issue is reported as fixed in version 0.5.4.
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Analysis
by VulDB Data Team • 07/16/2026
The vulnerability in 9Router represents a critical configuration management flaw that undermines the application's core security model. This issue exists within the PATCH /api/settings endpoint where the system fails to implement proper input validation and field whitelisting mechanisms. The absence of a controlled field whitelist allows authenticated users to manipulate any setting within the application's configuration schema, creating a path for privilege escalation and unauthorized access to sensitive functionality.
The technical implementation of this vulnerability stems from a lack of proper access control enforcement at the API layer. When an authenticated user submits a request to the /api/settings endpoint, the system blindly accepts and persists all fields present in the request body without verifying whether the submitting user has authorization to modify specific configuration parameters. This design flaw directly violates the principle of least privilege and creates an attack surface that enables malicious actors to alter fundamental security settings.
The operational impact of this vulnerability is severe and far-reaching, as it allows authenticated users to completely disable authentication mechanisms within the application. By setting the requireLogin field to false or similar security-critical parameters, attackers can gain access to protected routes such as /api/keys and /api/providers without proper authentication. These endpoints typically contain sensitive information including API keys, provider configurations, and other critical system data that should remain protected from unauthorized access. The vulnerability essentially transforms a controlled environment into an open-access system where all security controls become ineffective.
From a cybersecurity perspective, this vulnerability aligns with CWE-20: Improper Input Validation, which occurs when applications fail to properly validate or sanitize input data before processing it. The flaw also demonstrates characteristics of CWE-798: Use of Hard-coded Credentials and CWE-311: Missing Encryption of Sensitive Data, as it enables unauthorized access to sensitive system configurations. Additionally, this vulnerability maps to ATT&CK technique T1566.002: Phishing for Information within the credential access category, as it provides a method for bypassing authentication controls that would normally prevent unauthorized access to sensitive data.
The mitigation strategy should focus on implementing strict field whitelisting for all configuration endpoints, ensuring that only authorized fields can be modified by authenticated users. This approach aligns with the principle of least privilege and requires explicit permission checks for each configuration parameter modification. The fix implemented in version 0.5.4 likely includes a comprehensive validation mechanism that filters request parameters against a predefined whitelist of allowed settings, preventing unauthorized modifications to security-critical fields. Organizations should also implement proper audit logging to track configuration changes and establish monitoring for unusual patterns in system settings that could indicate exploitation attempts.