static long vnc_client_read_tls(gnutls_session_t *session, uint8_t *data,
                                size_t datalen)
{
    long ret = gnutls_read(*session, data, datalen);
    if (ret < 0) {
        if (ret == GNUTLS_E_AGAIN) {
            errno = EAGAIN;
        } else {
            errno = EIO;
        }
        ret = -1;
    }
    return ret;
}

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