Keycloak Policy Enforcer Authorization Bypass

Executive Summary

This vulnerability exists in the Keycloak Policy Enforcer component. It allows any authenticated user to bypass all authorization policies, including role-based, scope-based, and User-Managed Access (UMA) permission checks.

The bypass is achieved by including the configured access-denied page path within a request URL, either as a path segment or as a query parameter. This manipulation enables an attacker to gain unauthorized access to protected resources.

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Impact Analysis

This vulnerability can have a significant impact by allowing unauthorized access to protected resources. Since authorization policies can be bypassed, sensitive data or functionality intended to be restricted may be exposed to users who should not have access.

The CVSS score of 8.1 indicates a high severity, with high impact on confidentiality and integrity, meaning attackers can read or modify sensitive information without proper authorization.

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Compliance Impact

This vulnerability allows any authenticated user to bypass all authorization policies and gain unauthorized access to protected resources.

Such unauthorized access could lead to exposure of sensitive personal or protected health information, which may result in non-compliance with standards and regulations like GDPR and HIPAA that require strict access controls and protection of sensitive data.

Therefore, exploitation of this flaw could compromise compliance with these regulations by failing to enforce proper authorization and data protection.

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Detection Guidance

This vulnerability can be detected by monitoring requests to protected Keycloak endpoints that include the configured access-denied page path (defaulting to /access-denied) either as a path segment or as a query parameter.

One way to detect potential exploitation attempts is to search your web server or application logs for requests containing the string '/access-denied' in the URL.

• Use command-line tools like grep to scan logs, for example: grep '/access-denied' /var/log/keycloak/access.log
• Monitor network traffic for HTTP requests with URLs containing '/access-denied' using tools like tcpdump or Wireshark with appropriate filters.
• Check for unusual or unauthorized access patterns where authenticated users access protected resources by appending the access-denied path.

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Mitigation Strategies

Immediate mitigation steps include restricting access to the Keycloak Policy Enforcer component and monitoring for exploitation attempts.

Since a patch is not yet available and the vulnerability is under embargo until August 19, 2026, you should:

• Limit authenticated user access to trusted users only.
• Implement additional access controls or network-level restrictions to prevent unauthorized requests containing the access-denied path.
• Monitor logs and network traffic for suspicious requests that include the access-denied page path.
• Prepare to apply the official patch once it becomes available after the embargo period.

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