Project: 
Date: 
2026-June-17
Vulnerability: 
Cache poisoning and open redirect
Affected versions: 
<10.5.12 || >=10.6.0 <10.6.11 || >=11.2.0 <11.2.14 || >=11.3.0 <11.3.12 || 11.0.* || 11.1.*
CVE IDs: 
CVE-2026-55806
Description: 

Drupal core ships a rebuild.php front controller that can be used to rebuild Drupal (clearing the caches and rebuilding the container) when the site is in an unexpected condition.

This script doesn't correctly check the Host header against the list of trusted host patterns. This could result in cache poisoning or a redirect to an attacker-controlled domain.

Solution: 

Install the latest version:

Drupal 11

Drupal 10

Drupal 11.1.x, Drupal 11.0.x, Drupal 10.4.x, and below are end-of-life and do not receive security coverage. (Drupal 8 and Drupal 9 have both reached end-of-life.)

Fixed By: 
Coordinated By: