Ticket #33121: 33121.diff

src/wp-includes/kses.php

@@ -867 +867 @@
         $allowed_attr = $allowed_html[strtolower( $element )];
 
         $name_low = strtolower( $name );
+
+        // Allow `data-*` attributes.
+        // When filtering or specifying `$allowed_html`, the attribute name should be set as `data-*`
+        // (not to be mixed with the HTML 4.0 `data` attribute, see https://www.w3.org/TR/html40/struct/objects.html#adef-data).
+        // Note: the attribute name should only contain `A-Za-z0-9_-` chars.
+        if ( ! empty( $allowed_attr['data-*'] ) && preg_match( '/^data-[a-z0-9_-]+$/', $name_low, $match ) ) {
+                // Add the whole attribute name to the allowed attributes and set any restrictions
+                // for all `data-*` attribute values for this element.
+                $allowed_attr[ $match[0] ] = $allowed_attr['data-*'];
+        }
+
         if ( ! isset( $allowed_attr[$name_low] ) || '' == $allowed_attr[$name_low] ) {
                 $name = $value = $whole = '';
                 return false;
@@ -1820 +1831 @@
                 'style' => true,
                 'title' => true,
                 'role' => true,
+                'data-*' => true,
         );
 
         if ( true === $value )