Drupal 7 and 8 core highly critical release on March 28th, 2018 PSA-2018-001
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. Security release announcements will appear on the Drupal.org security advisory page.
While Drupal 8.3.x and 8.4.x are no longer supported and we don't normally provide security releases for unsupported minor releases, given the potential severity of this issue, we are providing 8.3.x and 8.4.x releases that include the fix for sites which have not yet had a chance to update to 8.5.0. The Drupal security team strongly recommends the following:Sites on 8.3.x should immediately update to the 8.3.x release that will be provided in the advisory, and then plan to update to the latest 8.5.x security release in the next month. Sites on 8.4.x should immediately update to the 8.4.x release that will be provided in the advisory, and then plan to update to the latest 8.5.x security release in the next month. Sites on 7.x or 8.5.x can immediately update when the advisory is released using the normal procedure.
The security advisory will list the appropriate version numbers for all three Drupal 8 branches. Your site's update report page will recommend the 8.5.x release even if you are on 8.3.x or 8.4.x, but temporarily updating to the provided backport for your site's current version will ensure you can update quickly without the possible side effects of a minor version update.
This will not require a database update.
Patches for Drupal 7.x and 8.3.x, 8.4.x, 8.5.x and 8.6.x will be provided.
The CVE for this issue is CVE-2018-7600. The Drupal-specific identifier for the issue is SA-CORE-2018-002.
The Security Team or any other party is not able to release any more information about this vulnerability until the announcement is made. The announcement will be made public at https://www.drupal.org/security, over Twitter, and in email for those who have subscribed to our email list. To subscribe to the email list: log in on drupal.org, go to your user profile page and subscribe to the security newsletter on the Edit » My newsletters tab.
If you find a security issue, please report it at https://www.drupal.org/security-team/report-issue.
updated 2018-03-22: Added information about database updates
updated 2018-03-27: Added information about patches
updated 2018-03-28: Added information about CVE and identifiers