CVE-2025-56404 is a vulnerability identified in MariaDB MCP version 0.1.0, specifically related to its SSE (Server-Sent Events) service. The core issue stems from the SSE service lacking proper user validation, which allows attackers to gain access to sensitive information. Server-Sent Events are a web technology enabling servers to push real-time updates to clients over HTTP connections. In this context, the SSE service in MariaDB MCP is expected to handle authenticated requests to deliver data streams securely. However, due to the absence of user validation, unauthorized actors can connect to the SSE endpoint and retrieve sensitive data that should otherwise be protected. Although the affected version is an early release (0.1.0), this vulnerability highlights a critical design flaw in access control mechanisms within the SSE implementation. No specific affected versions beyond 0.1.0 are listed, and no patches or fixes have been published yet. Additionally, there are no known exploits in the wild at this time. The lack of a CVSS score indicates that the vulnerability has not yet been fully assessed for severity, but the nature of unauthorized data disclosure through an unauthenticated channel is concerning. Since MariaDB MCP is a management and control platform for MariaDB databases, exposure of sensitive information via SSE could lead to leakage of database metadata, configuration details, or other confidential operational data, potentially aiding further attacks or reconnaissance.

For European organizations using MariaDB MCP 0.1.0, this vulnerability could result in unauthorized disclosure of sensitive information, undermining confidentiality and potentially aiding attackers in crafting more targeted attacks. The exposure of internal database management data could lead to increased risk of data breaches, compliance violations (e.g., GDPR), and reputational damage. Organizations relying on MariaDB MCP for critical database management may face operational risks if attackers leverage the leaked information to disrupt services or escalate privileges. Since the vulnerability does not require authentication, it increases the attack surface by allowing external or internal threat actors to exploit the flaw without valid credentials. The impact is particularly significant for sectors handling sensitive personal data or critical infrastructure, such as finance, healthcare, and government agencies within Europe. However, the absence of known exploits and the early version affected may limit immediate widespread impact, but the risk remains high if the vulnerability is not addressed promptly.

1. Immediate mitigation should include restricting network access to the SSE service endpoint, ensuring it is only accessible from trusted internal networks or via VPN to reduce exposure. 2. Implement additional authentication and authorization controls around the SSE service to enforce user validation before allowing access to any data streams. 3. Monitor network traffic and logs for unusual or unauthorized access attempts to the SSE endpoint. 4. Upgrade MariaDB MCP to a later version once a patch or fix addressing this vulnerability is released by the vendor. 5. If upgrading is not immediately possible, consider disabling the SSE service temporarily to eliminate the attack vector. 6. Conduct a thorough security review of the MariaDB MCP deployment to identify any other potential misconfigurations or vulnerabilities. 7. Educate system administrators and security teams about this vulnerability to ensure timely detection and response to any exploitation attempts.