This module enables you to manage blocks from specific modules in the specific themes.
The module doesn't sufficiently check permissions under the scenario when a block is added using the form "/admin/structure/block/add/{plugin_id}/{theme}" (route "block.admin_add"). The attacker can add the block to the theme where they can't manage blocks.
This vulnerability is mitigated by the fact that an attacker must have a role with the permission "administer blocks provided by [provider]".
- Greg Knaddison of the Drupal Security Team
- Juraj Nemec of the Drupal Security Team