static void zend_verify_abstract_class_function(zend_function *fn, zend_abstract_info *ai) /* {{{ */
{
	if (fn->common.fn_flags & ZEND_ACC_ABSTRACT) {
		if (ai->cnt < MAX_ABSTRACT_INFO_CNT) {
			ai->afn[ai->cnt] = fn;
		}
		if (fn->common.fn_flags & ZEND_ACC_CTOR) {
			if (!ai->ctor) {
				ai->cnt++;
				ai->ctor = 1;
			} else {
				ai->afn[ai->cnt] = NULL;
			}
		} else {
			ai->cnt++;
		}
	}
}
/* }}} */

The product uses a function that accepts a format string as an argument, but the format string originates from an external source.