I happened to come across this draft 
https://datatracker.ietf.org/doc/draft-lemmons-composite-claims/ and  noticed 
this statement:

Composition claims can be nested to an arbitrary level of depth.
   Implementations MAY limit the depth of composition nesting by

   rejecting CWTs with  too many levels but MUST support at least four

   levels of nesting.

I'm not a COSE expert, but this reminded me of a recursive stack problem attack 
that could occur in XML documents many years ago without proper mitigations.   
It might be good to suggest that Implementations SHOULD or even MUST limit the 
depth appropriate to their application constraints (or something like), or 
choose a maximum depth limit that makes sense (for example would anyone really 
need more than 100?).  I'm just worried that allowing unlimited nesting depths 
could cause a naïve parser to explode.

Cheers,

John Gray
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