CVE-2026-28695: Craft affected by authenticated RCE via Twig SSTI - create() function + Symfony Process gadget

Craft is a content management system (CMS). There is an authenticated admin RCE in Craft CMS 5.8.21 via Server-Side Template Injection using the create() Twig function combined with a Symfony Process gadget chain. The create() Twig function exposes Craft::createObject(), which allows instantiation of arbitrary PHP classes with constructor arguments. Combined with the bundled symfony/process dependency, this enables RCE. This bypasses the fix implemented for CVE-2025-57811 (patched in 5.8.7). This vulnerability is fixed in 5.9.0-beta.1 and 4.17.0-beta.1.