GHSA-86vw-x4ww-x467: Craft CMS: RCE via missing cleanseConfig in FieldsController::actionRenderCardPreview

July 9, 2026 (updated August 6, 2026)

The actionRenderCardPreview() method in FieldsController passes the fieldLayoutConfig POST parameter directly to Fields::createLayout() without calling Component::cleanseConfig(). This allows Yii2 event handler injection via on eventName keys in the config array, leading to arbitrary code execution.

This is the same vulnerability pattern that was fixed in GHSA-4484-8v2f-5748 (same file, _fldComponent method correctly uses cleanseConfig), GHSA-qx2q-q59v-wf3j (EntryTypesController), and GHSA-2fph-6v5w-89hh (ElementIndexesController).

References

Code Behaviors & Features

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