Chainlit: SSRF via MCP SSE and streamable-http transports allows unauthenticated internal network access
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(), allow
Chainlit: Command injection via MCP stdio transport allows unauthenticated remote code execution
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 stdio transport, the endpoint accepts a user-controlled fullCommand string. The validate_mcp_command() function in backend/chainlit/mcp.py checks only the executable name against config.features.mcp.stdio.allowed_executables and passes unchecked arguments to StdioServerParameters in backend/chainlit/server.py. Because npx supports the -c argument, an attacker can execute arb
Chainlit < 2.10.1 Session Hijacking via WebSocket Session Restoration
Chainlit before 2.10.1 contains a session hijacking vulnerability that allows unauthenticated attackers to restore and inherit authenticated user sessions by presenting a valid sessionId during WebSocket session restoration without ownership verification. Attackers can exploit the restore_existing_session path to assume a victim's permissions and roles, enabling unauthorized invocation of tools and access to data restricted to the authenticated victim.
Chainlit < 2.9.4 SQLAlchemy Data Layer SSRF via /project/element
Chainlit versions prior to 2.9.4 contain a server-side request forgery (SSRF) vulnerability in the /project/element update flow when configured with the SQLAlchemy data layer backend. An authenticated client can provide a user-controlled url value in an Element, which is fetched by the SQLAlchemy element creation logic using an outbound HTTP GET request. This allows an attacker to make arbitrary HTTP requests from the Chainlit server to internal network services or cloud metadata endpoints and store the retrieved responses via the configured storage provider.
Chainlit < 2.9.4 Arbitrary File Read via /project/element
Chainlit versions prior to 2.9.4 contain an arbitrary file read vulnerability in the /project/element update flow. An authenticated client can send a custom Element with a user-controlled path value, causing the server to copy the referenced file into the attacker’s session. The resulting element identifier (chainlitKey) can then be used to retrieve the file contents via /project/file/<chainlitKey>, allowing disclosure of any file readable by the Chainlit service.
Chainlit versions prior to 2.8.5 contain an authorization bypass through user-controlled key vulnerability. If this vulnerability is exploited, threads may be viewed or thread ownership may be obtained by an attacker who can log in to the product.