Ticket #57638: 57638.patch

wp-admin/includes/class-custom-image-header.php

@@ -332 +332 @@
                         if ( ! empty( $header['attachment_id'] ) ) {
                                 $width = ' width="230"';
                         }
-                        echo '<img src="' . set_url_scheme( $header_thumbnail ) . '" alt="' . esc_attr( $header_alt_text ) . '"' . $width . ' /></label>';
+                        echo '<img src="' . esc_url( set_url_scheme( $header_thumbnail ) ) . '" alt="' . esc_attr( $header_alt_text ) . '"' . $width . ' /></label>';
                         echo '</div>';
                 }