static int ipgre_close(struct net_device *dev)
{
	struct ip_tunnel *t = netdev_priv(dev);

	if (ipv4_is_multicast(t->parms.iph.daddr) && t->mlink) {
		struct in_device *in_dev;
		in_dev = inetdev_by_index(dev_net(dev), t->mlink);
		if (in_dev)
			ip_mc_dec_group(in_dev, t->parms.iph.daddr);
	}
	return 0;
}

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