session_by_channel(int id)
{
	int i;
	for (i = 0; i < sessions_nalloc; i++) {
		Session *s = &sessions[i];
		if (s->used && s->chanid == id) {
			debug("session_by_channel: session %d channel %d",
			    i, id);
			return s;
		}
	}
	debug("session_by_channel: unknown channel %d", id);
	session_dump();
	return NULL;
}

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