Answering this request first requires some clarification. Is the boss taking advantage of something you did, or of something someone else, not even member of his team, did ?

It's common practice in scientifical teams that the lead researcher appears as author of any discovery, even when most of the job has been done by obscure sub-workers...

This might seem unfair, but after all, he's the boss, he put the context in place, decided where to look at, probably fought for the funding, and so on. Without him doing that, there would be no research and no discovery at all.

On top of that, the "obscure" coworkers build up experience, benefit from the boss public aura, and will later be in position to become the boss themselves. This is the work version of King Leo "Cycle of Life".

On the other hand, no one shall be allowed to get credit from someone else's work, namely from another team, or company. Not only this is morally questionable, but it can also have serious legal repercusions.

If you try to discuss the subject with your boss or colleagues (are you REALLY sure you want to do that ?), don't get fooled by arguments like "I do it for the team", "They would be ok anyway", or "No one will know".

However, before bringing that on the table, make sure he's actually doing that. Could there be some agreements you're not aware of ? Are you really sure he did not made it ?

I personally can't work for someone I don't trust, or don't beleive in. But are you ready to start a fight against your boss ? What would you then aim at ? Taking over his job ? Leaving the team ? Simply making him aware of your opinion ?

The "career" tag on this hub is really appropriate. Going against your boss can have serious impact on your career, both positive or negative. So if you want to the whistleblowing way have a plan, and be ready for a rough ride !