Magento Commerce versions 2.4.2 (and earlier), 2.4.2-p1 (and earlier) and 2.3.7 (and earlier) are affected by a Path Traversal vulnerability via the `theme[preview_image]` parameter. An attacker with admin privileges could leverage this vulnerability to achieve remote code execution.
https://helpx.adobe.com/security/products/magento/apsb21-64.html