static char *addr_to_string(const char *format,
                            struct sockaddr_storage *sa,
                            socklen_t salen) {
    char *addr;
    char host[NI_MAXHOST];
    char serv[NI_MAXSERV];
    int err;
    size_t addrlen;

    if ((err = getnameinfo((struct sockaddr *)sa, salen,
                           host, sizeof(host),
                           serv, sizeof(serv),
                           NI_NUMERICHOST | NI_NUMERICSERV)) != 0) {
        VNC_DEBUG("Cannot resolve address %d: %s\n",
                  err, gai_strerror(err));
        return NULL;
    }

    /* Enough for the existing format + the 2 vars we're
     * substituting in. */
    addrlen = strlen(format) + strlen(host) + strlen(serv);
    addr = g_malloc(addrlen + 1);
    snprintf(addr, addrlen, format, host, serv);
    addr[addrlen] = '\0';

    return addr;
}

This category addresses vulnerabilities caused by flawed access control mechanisms, where incorrect permission settings allow unauthorized users to access restricted resources.