The (1) Textimage 4.7.x before 4.7-1.2 and 5.x before 5.x-1.1 module for Drupal and the (2) Captcha 4.7.x before 4.7-1.2 and 5.x before 5.x-1.1 module for Drupal allow remote attackers to bypass the CAPTCHA test via an empty captcha element in $_SESSION.