There will be a security release of Drupal 7.x, 8.4.x, and 8.5.x on April 25th, 2018 between 16:00 - 18:00 UTC. This PSA is to notify that the Drupal core release is outside of the regular schedule of security releases. For all security updates, the Drupal Security Team urges you to reserve time for core updates at that time because there is some risk that exploits might be developed within hours