CVE-2026-6060 – QUIC Handshake Amplification via Address Validation Bypass

Program Code (Python simulation)

# quic_server_sim.py - Vulnerable QUIC server (simulated handshake)
import socket

def send_quic_initial(conn, addr, server_salt):
    # Respond with a large "server hello" without validating source address
    # In real QUIC, the server must echo the client's token; here we skip that.
    payload = b'\x00' * 1200  # large response
    conn.sendto(payload, addr)

server_socket = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
server_socket.bind(('0.0.0.0', 4433))
print("QUIC server on :4433")

while True:
    data, addr = server_socket.recvfrom(1024)
    # Vulnerability: respond to any initial packet, no token verification
    send_quic_initial(server_socket, addr, b'salt')

CVE-2026-6060 – QUIC Handshake Amplification via Address Validation Bypass

Overview

A QUIC server implementation fails to enforce source address validation during the handshake, allowing an attacker to send a small initial packet with a spoofed source IP. The server responds with a much larger packet, enabling DDoS amplification.

Vulnerability Details

• Type: Amplification Attack
• Impact: Network reflection, DDoS.
• Root Cause: The server does not require the client to echo a token (address validation) before sending a large server hello, violating RFC 9000.

Exploit Demonstration

1. Start the vulnerable QUIC server:
   root@kitploit:~

   python quic_server_sim.py
   

2. In a real attack, an attacker would send a spoofed UDP packet. For demonstration, I will just show the amplification factor: a 1‑byte request elicits a 1200‑byte response.