static int addmbox_to_list(const mbentry_t *mbentry, void *rock)
{
    strarray_t *list = (strarray_t *)rock;
    strarray_append(list, mbentry->name);
    return 0;
}

The product receives input or data, but it does not validate or incorrectly validates that the input has the properties that are required to process the data safely and correctly.