Ticket #51855: 51855.diff

src/wp-includes/category-template.php

@@ -398 +398 @@
         $categories = get_terms( $get_terms_args );
 
         $name     = esc_attr( $parsed_args['name'] );
-        $class    = esc_attr( $parsed_args['class'] );
+        $class    = sanitize_html_class( $parsed_args['class'] );
         $id       = $parsed_args['id'] ? esc_attr( $parsed_args['id'] ) : $name;
         $required = $parsed_args['required'] ? 'required' : '';