CVE Request: BGP protocol vulnerability

[Florian Weimer <fw () deneb enyo de>]

The BGP protocol and its various extensions require that BGP peering
sessions are terminated when a peer receives a BGP update message
which it considers semantically incorrect, leading to a persistent
denial-of-service condition if the update is received again after the
terminated session is reestablished.

(This is not something new at all---we just need to get up, treat it
as a vulnerability, and fix it.)