"There will be a security release of Drupal 7.x, 8.3.x, 8.4.x, and 8.5.x on March 28th 2018 between 18:00 - 19:30 UTC, one week from the publication of this document, that will fix a highly critical security vulnerability. The Drupal Security Team urges you to reserve time for core updates at that time because exploits might be developed within hours or days."
url:
https://www.drupal.org/psa-2018-001
331