I have reviewed this document as part of the security directorate's ongoing effort to review all IETF documents being processed by the IESG.  These comments were written primarily for the benefit of the security area directors.  Document editors and WG chairs should treat these comments just like any other last call comments.

The security ADs may prefer to see an elaborated Security Considerations section. From my perspective, the single sentence seeking to ensure that malformed TLV and Sub-TLV permutations don't result in hard OSPF failures is insufficient. What could be the outcome of such hard failures (i.e. what does an implementer need to understand about not heeding such considerations)? Also, a reader might presume that there are no additional BIER security considerations not otherwise handled in RFCs 8279 and 8296 respectively. If such a presumption is correct, then I would recommend explicitly stating so and perhaps even referring the reader to those Security Considerations for anything that may apply to this extension. Finally, in the first sentence of the Security Considerations, there exists "must" - is that intended to be MUST?

I don't have any further comments on this draft from a nit perspective nor from an efficacy perspective when it comes to routing, as this isn't my area of expertise.

Kind regards,

Adam