The text in 4.4.2 (first bullet) now simply reads:

                                                       This will lead
      to multiplexing on an association to the wrong node if signalling
      nodes have colliding Peer-Identities and one is reachable at the
      same Interface-Address as another.  This could be done by an on-
      path attacker; on-path attacks are discussed further in
      Section 8.7.

8.7 contains the old discussion of why we don't attempt to prevent off-path
attacks non-cryptographically.

The case of colliding interface-address and peer-identity should be described
more objectively than simply being called a failure, and there should be a
reference to the protection/recovery mechanisms.

(Actually, protection/recovery in this case is intrinsically hard since this is
a case of an on-path attack which we don't attempt to handle. This issue, and
the related topic of peer node authentication, are discussed later in the
security considerations section.)