Sigh....I didn’t want to geek out too much with this...but here goes...

Short version: ebony as used in finished musical instruments isn't covered. Long version follows.
CITES uses 3 Appendices to list the various species that are covered by the treaty, called Appendix I, II and III.
The appendix to which a given species is classified defines the degree of protection it is given by the treaty.
Appendix I covers species that are threatened with extinction, and those species basically cannot be traded internationally. For our purposes, common bass (or guitar) materials on Appendix I include Brazilian rosewood, ivory (from elephants or mammoths) and real tortoiseshell (not the plastic stuff!).
Appendix II covers species that are at risk, but not yet threatened with extinction. Those products are subject to all kinds of harvesting, export and import restrictions which vary by species, but can be traded internationally with the right paperwork.The genus
dalbergia is in Appendix II except for
dalbergia nigra (Brazilian rosewood), which is in Appendix I. FYI, cocobolo, tulipwood and bubinga are all species in the
dalbergia genus, so they are in Appendix II. The Appendix II restrictions on
dalbergia currently cover "all parts and derivatives," which means anything with an Appendix II wood in it. (There is supposed to be a less than 10kg exemption for non-commercial cross-border transfers - search this thread for more on that if you care about it).
Ebony - but only ebony from Madagascar - is listed in Appendix II, but only the international trade of "logs, sawn wood, veneer sheets and plywood" is covered. Your bass probably isn't any of those things, so you are good to go.
Appendix III covers species that are requested for coverage by a particular country. Don't worry about those.
Here's a link to the CITES appendices at the official CITES website:
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In the US, CITES enforcement is handled by the US Fish & Wildlife Service. Here's their list of covered plant species, which is handy because it uses common names, not just the Latin genus/species nomenclature:
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BTW, and as discussed above, there is a proposal pending before the CITES convention literally this week that will exempt "finished musical instruments and finished musical instrument parts" from all Appendix II restrictions.