View online: https://www.drupal.org/node/2907137

* Advisory ID: DRUPAL-SA-CONTRIB-2017-073 * Project: CAPTCHA [1] (third-party module) * Version: 7.x * Date: 2017-September-06 * Security risk: 10/25 ( Moderately Critical) AC:Basic/A:None/CI:None/II:None/E:Proof/TD:Default [2] * Vulnerability: Denial of Service

-------- 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 [3] 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 [4] module, there is nothing you need to do.

-------- SOLUTION ------------------------------------------------------------

Install the latest version:

* If you use the CATPCHA module for Drupal 7.x, upgrade to CAPTCHA 7.x-1.5. [5]

Also see the CAPTCHA [6] project page.

-------- REPORTED BY ---------------------------------------------------------

* Nightwalker3000 [7]

-------- FIXED BY ------------------------------------------------------------

* Fabiano Sant'Ana [8], the module's maintainer.

-------- COORDINATED BY ------------------------------------------------------

* Lee Rowlands [9] of the Drupal Security Team. * Damien McKenna [10] of the Drupal Security Team.

-------- 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 [11].

Learn more about the Drupal Security team and their policies [12], writing secure code for Drupal [13], and securing your site [14].

Follow the Drupal Security Team on Twitter at https://twitter.com/drupalsecurity [15]

[1] https://www.drupal.org/project/captcha [2] https://www.drupal.org/security-team/risk-levels [3] http://cve.mitre.org/ [4] https://www.drupal.org/project/captcha [5] https://www.drupal.org/project/captcha/releases/7.x-1.5 [6] https://www.drupal.org/project/captcha [7] https://www.drupal.org/u/nightwalker3000 [8] https://www.drupal.org/u/wundow [9] https://www.drupal.org/u/larowlan [10] https://www.drupal.org/u/damienmckenna [11] https://www.drupal.org/contact [12] https://www.drupal.org/security-team [13] https://www.drupal.org/writing-secure-code [14] https://www.drupal.org/security/secure-configuration [15] https://twitter.com/drupalsecurity