CERN Base Theme has been updated to version 7.x-2.5. This version fixes the visual issues seen in Webforms (description in textareas) and CAPTCHA module.
You will receive an email from Drupal admins when the new Theme will be available in development and production websites.
Meanwhile, if you want to test it you can clone it locally with Git under your themes folder:
git clone https://git.cern.ch/reps/webteam-cern_base
You should clear the cache after that.