Executive Summary

CVE-2025-56405 is an unauthorized access vulnerability in the litmus-mcp-server's Server-Sent Events (SSE) endpoint. The server does not verify the identity of users connecting to the SSE endpoint, allowing any user to connect without authentication. Additionally, the server binds by default to the IP address 0.0.0.0, exposing the service to all network interfaces. This combination allows attackers to connect to the MCP service and control it without authorization. [1, 2]

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Impact Analysis

This vulnerability allows unauthorized attackers to gain control over the litmus-mcp-server's MCP service remotely without any authentication or privileges. An attacker can connect to the server's SSE endpoint and manipulate the MCP, potentially leading to unauthorized control of multi-cloud platform operations. This can result in security breaches, data manipulation, or disruption of services. [1, 2]

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Detection Guidance

This vulnerability can be detected by attempting to connect to the litmus-mcp-server SSE endpoint without authentication. For example, if the server is running with default settings (binding to 0.0.0.0 and port 8000), you can test unauthorized access by using tools like curl or the MCP tool to connect to the SSE endpoint and check if control over the MCP service is possible. A sample command to run the server for testing is: `docker run -d --name litmus-mcp-server -p 8000:8000 ghcr.io/litmusautomation/litmus-mcp-server:main`. Then, use a command like `curl http://<server-ip>:8000/sse-endpoint` (replace `/sse-endpoint` with the actual SSE path) to see if the connection is accepted without authentication. [1, 2]

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Mitigation Strategies

Immediate mitigation steps include: 1) Deploy the litmus-mcp-server within a restricted network environment such as behind a VPN or internal network to limit access to trusted IP addresses. 2) Configure host or network firewalls to restrict inbound connections to port 8000 (default service port), allowing only authorized clients. 3) Avoid exposing the service directly to the public internet. 4) Monitor official vendor channels for patches or updates and apply them promptly once available. Long-term remediation involves implementing robust authentication and authorization mechanisms for the service. [2]

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