Affected: Packagist:https://packages.drupal.org/8: drupal/webform

The Webform module allows site builders to create forms, collect submissions, and configure access to forms and submission data.

When Webform is used with JSON:API enabled, submissions may be cached without varying correctly by the authenticated user. If a webform is configured so that authenticated users can view their own submissions, a request to the JSON:API webform submission collection can return a cached response generated for a different user.

This can allow an authenticated user to view another user's webform submission data through the JSON:API collection endpoint.

This vulnerability is mitigated by the fact that JSON:API must be enabled, the affected webform must expose submissions through JSON:API, and the attacker must have an account with permission to view their own submissions for the affected webform.