The EWWW Image Optimizer WordPress plugin before 8.8.0 does not confine a WebP-derivative file migration routine to the current site's own uploads directory, letting an attacker with Administrator-level access rename or delete existing WebP-derivative image files outside that scope, including, on a multisite network, files belonging to a different site they have no access to.

EWWW Image Optimizer before 2.8.5 allows remote command execution because it relies on a protection mechanism involving boolval, which is unavailable before PHP 5.5.

Cross-site scripting (XSS) vulnerability in the EWWW Image Optimizer plugin before 2.0.2 for WordPress allows remote attackers to inject arbitrary web script or HTML via the error parameter in the ewww-image-optimizer.php page to wp-admin/options-general.php, which is not properly handled in a pngout error message.