CyberRota Analysis
AI-GeneratedChainlit deployments with the features.mcp.enabled setting exposed the POST /mcp endpoint without authentication, allowing attackers to send arbitrary requests to internal or external services, including sensitive cloud metadata endpoints. This vulnerability can lead to unauthorized access, service discovery, and potential data exfiltration due to the lack of scheme validation and filtering on user-controlled URLs and headers. Organizations using affected versions of Chainlit, particularly those with enabled MCP features, should prioritize upgrading to version 2.12.0 to mitigate these risks.
Public Exploit Signal
A public exploit, PoC, GitHub repository or Metasploit reference was detected for this CVE.
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Original NVD Description
Chainlit is a Python framework for building production-ready conversational AI applications. From 2.4.0rc0 until 2.12.0, Chainlit deployments with features.mcp.enabled set to true in .chainlit/config.toml expose the POST /mcp endpoint without requiring authentication. For sse and streamable-http transports, ConnectSseMCPRequest and ConnectStreamableHttpMCPRequest in backend/chainlit/types.py accept a user-controlled url and optional headers dictionary without scheme validation, private-address filtering, or an allowlist. The connect_mcp handler in backend/chainlit/server.py passes these values to sse_client() or streamablehttp_client(), allowing the Chainlit server to make blind outbound requests to arbitrary internal or external services, including cloud metadata endpoints, with attacker-controlled Authorization and Cookie headers. The SSE URL sink has existed since 2.4.0rc0, while attacker-controlled header forwarding and streamable-http support were added in 2.6.4. The response is consumed internally and not returned, but the attacker can issue state-changing authenticated requests, discover internal services, scan ports, and probe metadata endpoints. This issue is fixed in version 2.12.0.