CAPTCHA - Moderately Critical - Denial of Service - SA-CONTRIB-2017-073

Description

This module enables you to use various techniques to block automated scripts / robots from submitting content to a site, e.g. to block spam comments.

The module doesn't properly store the session ID of visitors who are given a session which could lead to a Denial of Service attack.

This vulnerability is mitigated by the fact that Drupal does not give a session to all visitors, especially when used with advanced caching systems like Varnish.

CVE identifier(s) issued

  • A CVE identifier will be requested, and added upon issuance, in accordance with Drupal Security Team processes.

Versions affected

  • CAPTCHA 7.x-1.x versions prior to 7.x-1.5.

Drupal core is not affected. If you do not use the contributed CAPTCHA module, there is nothing you need to do.

Solution

Install the latest version:

Also see the CAPTCHA project page.

Reported by

Fixed by

Coordinated by

Contact and More Information

The Drupal security team can be reached at security at drupal.org or via the contact form at https://www.drupal.org/contact.

Learn more about the Drupal Security team and their policies, writing secure code for Drupal, and securing your site.

Follow the Drupal Security Team on Twitter at https://twitter.com/drupalsecurity