I don't see any security concerns as we don't define any new protocol.
I have a small suggestion though:
The Abstract of the draft somehow doesn't truly reflect the actual description of the draft. This draft analyzes how NAT 64 confirms to RFC 4966, which problems mentioned in 4966 are solved, which are not solved etc. Whereas the abstract mentions "This document evaluate how the new stateful translation mechanisms avoid the problems that caused the IETF to deprecate NAT-PT." I think we can be more specific here.

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