void start_auth_vnc(VncState *vs)
{
    make_challenge(vs);
    /* Send client a 'random' challenge */
    vnc_write(vs, vs->challenge, sizeof(vs->challenge));
    vnc_flush(vs);

    vnc_read_when(vs, protocol_client_auth_vnc, sizeof(vs->challenge));
}

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