CVE-2025-3501: Keycloak Verification Policy Flaw Allows Bypass of Trust Store Certificate Verification

Overview

In the landscape of cybersecurity, vulnerabilities pose a constant threat to the integrity, confidentiality, and availability of data. One such vulnerability has been identified in Keycloak, a widely used open-source software product that offers single sign-on with Identity Management and Access Management aimed at modern applications and services. This vulnerability has the potential to impact a large number of organizations that rely on Keycloak for their identity and access management needs. The flaw, tagged as CVE-2025-3501, allows attackers to bypass the trust store certificate verification process, leading to potential system compromise or data leakage.

Vulnerability Summary

CVE ID: CVE-2025-3501
Severity: High (CVSS: 8.2)
Attack Vector: Network
Privileges Required: Low
User Interaction: None
Impact: System compromise and potential data leakage

Affected Products

Product | Affected Versions

Keycloak | All versions before the vendor patch

How the Exploit Works

The flaw in Keycloak resides in the verification policy. When the policy is set to ‘ALL’, the trust store certificate verification is skipped. The trust store certificate verification is a crucial part of the authentication process as it confirms the authenticity of the server. By bypassing this step, an attacker can impersonate the server or intercept the communication between the client and the server, leading to a potential compromise of the system and data leakage.

Conceptual Example Code

A conceptual example of how the vulnerability might be exploited might involve a malicious actor intercepting and modifying an HTTPS request. Please note that this is a simplified and non-functional example intended to illustrate the vulnerability:

GET /auth/realms/master/protocol/openid-connect/auth HTTP/1.1
Host: vulnerable-keycloak-server.com
User-Agent: Mozilla/5.0
{
"response_type": "code",
"client_id": "legitimate-client-id",
"redirect_uri": "https://malicious-actor.com/fake_redirect",
"state": "..."
}

In this example, a malicious actor could modify the ‘redirect_uri’ parameter to redirect the authorization code to a malicious server. This would allow the actor to gather potentially sensitive information and compromise the system.

Mitigation and Recommendations

The most effective way to mitigate this vulnerability is to apply the vendor patch as soon as it’s available. Until then, as a temporary measure, organizations can use a Web Application Firewall (WAF) or an Intrusion Detection System (IDS) to detect and block malicious traffic patterns related to this vulnerability. Additionally, organizations should also consider reviewing their certificate verification policies and ensure they are configured correctly.