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.


Install the latest version:

Also see the CAPTCHA project page.

Reported by

Fixed by

Coordinated by

Contact and More Information

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