GMS-2015-48: Potential Information Disclosure and Insufficient Entropy in Zend\Captcha\Word

Zend generates a “word” for a CAPTCHA challenge by selecting a sequence of random letters from a character set. The selection is performed using PHP’s internal array_rand() function. This function does not generate sufficient entropy due to its usage of rand() instead of more cryptographically secure methods such as openssl_pseudo_random_bytes(). This can potentially lead to information disclosure should an attacker be able to brute force the random number generation.