GHSA-957r-qf9p-67xw: Craft CMS: Arbitrary file read via SplFileObject in non-sandboxed template contexts

The create() Twig function (introduced in 5.9.0) allows instantiation of arbitrary PHP classes from template code, restricted only by a 5-entry blocklist. SplFileObject is not in the blocklist, enabling arbitrary file read, including .env (security key, DB credentials) and the passwd file from non-sandboxed Twig template contexts, such as entry type title formats and URI formats.

The sandbox correctly blocks create() in system email templates, so this finding applies only to admin-configured, non-sandboxed contexts that require allowAdminChanges=true.