In Math/BinaryField.php in phpseclib 3 before 3.0.34, excessively large degrees can lead to a denial of service.
https://github.com/phpseclib/phpseclib/releases/tag/3.0.34
https://github.com/phpseclib/phpseclib/commit/964d78101a70305df33f442f5490f0adb3b7e77f