Executive Summary

CVE-2026-5832 is a Server-Side Request Forgery (SSRF) vulnerability in the api-lab-mcp project, affecting versions up to 0.2.1. It occurs because attacker-controlled input provided via the `source` or `url` parameters in certain API endpoints is not sanitized before being used in outbound HTTP requests made by the server using functions like `fetch` or `axios`.

This lack of input validation allows an attacker with network access to the MCP/HTTP interface to coerce the server into making arbitrary HTTP requests to internal services, cloud metadata endpoints, or other restricted network locations. The vulnerable code paths include the tool handlers `test_http_endpoint`, `analyze_api_spec`, and `generate_test_scenarios`.

The root cause is that the server directly uses unsanitized `source` or `url` parameters from the request body as targets for outbound HTTP requests, enabling attackers to exploit internal network resources or sensitive endpoints.

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Impact Analysis

This vulnerability can have several impacts if exploited:

• Confidentiality: High risk of unauthorized information disclosure if internal services or cloud metadata endpoints are accessible, potentially exposing sensitive data.
• Integrity: Low to medium risk depending on whether the attacker can access internal write-capable APIs, possibly allowing modification of data.
• Availability: Low to medium risk due to potential request flooding or slow responses from internal targets, which could degrade service availability.

The attack can be carried out remotely without authentication, making it easier for attackers to exploit if the MCP/HTTP interface is exposed.

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Detection Guidance

This vulnerability can be detected by monitoring and analyzing requests made to the MCP/HTTP interface, specifically looking for JSON-RPC calls to the vulnerable tool handlers: test_http_endpoint, analyze_api_spec, and generate_test_scenarios, which include attacker-controlled source or url parameters.

Detection involves identifying outbound HTTP requests initiated by the server to unexpected or internal network destinations, especially those triggered by these parameters.

Suggested commands include capturing and inspecting network traffic or logs for suspicious outbound requests. For example, using curl or HTTP client tools to simulate or detect such requests:

• Use tcpdump or Wireshark to monitor outbound HTTP requests from the server to internal IP ranges or unusual destinations.
• Check server logs for JSON-RPC requests containing source or url parameters pointing to internal or attacker-controlled addresses.
• Example curl command to test the vulnerable endpoint (replace <server> and <port>): curl -X POST http://<server>:<port>/mcp -H 'Content-Type: application/json' -d '{"jsonrpc":"2.0","method":"test_http_endpoint","params":{"source":"http://127.0.0.1:8000"},"id":1}'
• Use tools like curl or Postman to send similar JSON-RPC requests to analyze_api_spec or generate_test_scenarios with attacker-controlled URLs to verify if the server makes outbound requests.

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Mitigation Strategies

Immediate mitigation steps include enforcing strict allowlists for outbound URLs to restrict the scheme, host, port, and path of requests initiated by the vulnerable tools.

Block requests to loopback addresses, link-local addresses, RFC1918 private IP ranges, and cloud metadata endpoints after DNS resolution and redirect handling.

Add authentication, authorization, logging, and rate limiting on the MCP/HTTP handlers that expose the vulnerable functionality to reduce the risk of exploitation.

Avoid exposing the MCP/HTTP interface to untrusted networks or users until a patch is applied.

The recommended fix involves removing the direct flow of attacker-controlled input to outbound HTTP request functions by implementing input schema validation and restricting source and url parameters to approved destinations.

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Compliance Impact

The vulnerability CVE-2026-5832 is a Server-Side Request Forgery (SSRF) that allows an attacker to coerce the server into making arbitrary HTTP requests to internal or restricted network destinations. This can lead to unauthorized information disclosure, which impacts the confidentiality of sensitive data.

Such unauthorized disclosure of sensitive or personal data could potentially violate compliance requirements under common standards and regulations like GDPR or HIPAA, which mandate the protection of personal and sensitive information against unauthorized access or leaks.

The vulnerability's high confidentiality impact means that if exploited, it could result in breaches of data privacy and security obligations required by these regulations.

Mitigations such as strict allowlists, blocking requests to internal IP ranges, and adding authentication and authorization controls are necessary to reduce the risk of non-compliance due to this vulnerability.

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