The Drupal Security Team just released an PSA (Public Service Announcement) regarding a Drupal 7 and 8 core critical release on April 25th: https://www.drupal.org/psa-2018-003
The security release is scheduled to be released on April 25th 2018 16:00 - 18:00 UTC.
We will investigate the possibility of a platform-wide temporary mitigation as soon as the security fix has been released and we have more information. It is not possible to say if a platform wide mitigation is possible at this time. We will keep you up to date as we learn more.
*We suggest all our clients to prepare to update their Drupal sites within a couple of hours after the release.*