Drupal 8 before 8.2.8 and 8.3 before 8.3.1 allows critical access bypass by authenticated users if the RESTful Web Services (rest) module is enabled and the site allows PATCH requests.

When adding a private file via the editor in Drupal 8.2.x before 8.2.7, the editor will not correctly check access for the file being attached, resulting in an access bypass.

Some administrative paths in Drupal 8.2.x before 8.2.7 did not include protection for CSRF. This would allow an attacker to disable some blocks on a site. This issue is mitigated by the fact that users would have to know the block ID.

A 3rd party development library including with Drupal 8 development dependencies is vulnerable to remote code execution. This is mitigated by the default .htaccess protection against PHP execution, and the fact that Composer development dependencies aren't normal installed. You might be vulnerable to this if you are running a version of Drupal before 8.2.2. To be sure you aren't vulnerable, you can remove the <siteroot>/vendor/phpunit directory from your production deployments

Confirmation forms in Drupal 7.x before 7.52 make it easier for remote authenticated users to conduct open redirect attacks via unspecified vectors.

The user password reset form in Drupal 8.x before 8.2.3 allows remote attackers to conduct cache poisoning attacks by leveraging failure to specify a correct cache context.

The taxonomy module in Drupal 7.x before 7.52 and 8.x before 8.2.3 might allow remote authenticated users to obtain sensitive information about taxonomy terms by leveraging inconsistent naming of access query tags.

The transliterate mechanism in Drupal 8.x before 8.2.3 allows remote attackers to cause a denial of service via a crafted URL.

Cross-site scripting (XSS) vulnerability in Drupal 8.x before 8.1.10 allows remote attackers to inject arbitrary web script or HTML via vectors involving an HTTP exception.

Drupal 8.x before 8.1.10 does not properly check for "Administer comments" permission, which allows remote authenticated users to set the visibility of comments for arbitrary nodes by leveraging rights to edit those nodes.